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![](media/image2.jpeg){width="6.5in" height="0.23958333333333334in"}

**BTeV C0 IR Quadrupole Magnet**

**Inner and Outer Cable Manufacturing Specification**

**Spec #: 5500-ES-371014**

January 27, 2005

The low beta quadrupoles for the BTeV C0 IR employ a two-layer design
with different cable parameters and superconducting strand in each
layer. The magnetic design of the BTeV low beta quadrupoles is based on
that of the LHC IR quadrupoles currently being fabricated at Fermilab,
differing only in the details of the iron yoke; the outer diameter of
the yoke is smaller and there are differences in bus and flow
passageways. The collared coil assembly is identical to that of the LHC
IR quadrupoles, and the cable and strand specifications are similar to
the specifications for the LHC IR quadrupoles.

The strand specifications for the BTeV C0 IR quadrupole magnets are:

-   Inner strand: 5500-ES-371009

-   Outer strand: 5500-ES-371010

**CONTENTS**

1 SCOPE [3](#scope)

1.1 Cable definition [3](#cable-definition)

2 REFERENCE DOCUMENTS [3](#reference-documents)

3 REQUIREMENTS [3](#requirements)

3.1 Technical requirements for strands
[3](#technical-requirements-for-strands)

3.2 Technical requirements for cable
[4](#technical-requirements-for-cable)

3.2.1 Mechanical properties [4](#mechanical-properties)

3.2.2 Electrical properties [5](#electrical-properties)

3.3 Processing [6](#processing)

3.3.1 Cable manufacturing [6](#cable-manufacturing)

3.3.2 Cable dimensions [6](#cable-dimensions)

3.3.3 Identification [6](#identification)

3.3.4 Cable Map [6](#cable-map)

3.3.5 Cable production lengths [6](#cable-production-lengths)

3.3.6 Strand Welds [7](#strand-welds)

3.3.7 Cable surface condition [7](#cable-surface-condition)

3.3.8 Crossover or broken strands [7](#crossover-or-broken-strands)

3.3.9 Sharp edges [7](#sharp-edges)

3.3.10 Degradation during cabling [7](#degradation-during-cabling)

3.3.11 Annealing [7](#annealing)

3.3.12 Reels/Spools [7](#reelsspools)

3.3.13 Spooling requirements [7](#spooling-requirements)

4 QUALITY ASSURANCE AND MANUFACTURING PLAN
[8](#quality-assurance-and-manufacturing-plan)

4.1 Quality Control Plan [8](#quality-control-plan)

4.2 Manufacturing plan [9](#manufacturing-plan)

4.3 Certificate of compliance [9](#certificate-of-compliance)

4.3.1 Nonconforming material [9](#nonconforming-material)

4.4 Submission of test samples [9](#submission-of-test-samples)

5 SHIPPING AND IDENTIFICATION REQUIREMENT
[10](#shipping-and-identification-requirement)

Appendix I - Procedure for the Measurement of Cable Dimensions
[11](#appendix-i---procedure-for-the-measurement-of-cable-dimensions)

I.1 Cable dimensions [11](#i.1-cable-dimensions)

I.2 Calibration of the Cable Measuring Machine and gauge checks
[11](#i.2-calibration-of-the-cable-measuring-machine-and-gauge-checks)

I.3 Checks at the beginning of the run
[11](#i.3-checks-at-the-beginning-of-the-run)

I.4 Checks at the end of the run [11](#i.4-checks-at-the-end-of-the-run)

Appendix II - Mechanical Tests [13](#appendix-ii---mechanical-tests)

Appendix III - Cable Critical Current Determination
[14](#appendix-iii---cable-critical-current-determination)

III.1 Introduction [14](#iii.1-introduction)

III.2 Definition of Critical Current
[14](#iii.2-definition-of-critical-current)

III.3 Sample Mounting [15](#iii.3-sample-mounting)

III.4 Electrical Instrumentation [16](#iii.4-electrical-instrumentation)

III.5 Measurement Procedure [16](#iii.5-measurement-procedure)

III.6 Temperature Calculation [17](#iii.6-temperature-calculation)

III.7 Magnetic Field Correction [17](#iii.7-magnetic-field-correction)

III.8 Critical Current of the Thin Edge:
[18](#iii.8-critical-current-of-the-thin-edge)

Appendix IV - Cable R(295) and RRR Determination
[19](#appendix-iv---cable-r295-and-rrr-determination)

Appendix V - Cable Sharp Edge [20](#appendix-v---cable-sharp-edge)

Appendix VI - Measurement of Degradation During Cabling
[21](#appendix-vi---measurement-of-degradation-during-cabling)

Appendix VII - Packaging and shipping of Superconducting Cable
[22](#appendix-vii---packaging-and-shipping-of-superconducting-cable)

#   {#section .unnumbered}

# 1 SCOPE {#scope .unnumbered}

This specification establishes the requirements for the fabrication,
inspection, test, identification and delivery of superconducting NbTi
cable for Fermilab BTeV C0 IR quadrupole magnets.

## 1.1 Cable definition {#cable-definition .unnumbered}

The cable is composed of superconducting strands, which are twisted
around a hollow core and pressed into a keystoned shape. Two types of
cable are required, one for the inner coils and one for the outer coils.

# 2 REFERENCE DOCUMENTS {#reference-documents .unnumbered}

The following documents form a part of this specification to the extent
specified herein:

5520-MA-439043 BTeV C0 IR Quadrupole Magnet Inner Bare Cable drawing

5520-MA-439044 BTeV C0 IR Quadrupole Magnet Outer Bare Cable drawing

5500-ES-371009 BTeV C0 IR Quadrupole Magnet Inner Strand Specification

5500-ES-371010 BTeV C0 IR Quadrupole Magnet Outer Strand Specification

# 3 REQUIREMENTS {#requirements .unnumbered}

## 3.1 Technical requirements for strands {#technical-requirements-for-strands .unnumbered}

The strands should be fabricated according to specifications
5500-ES-371009 (inner strand) or 5500-ES-371010 (outer strand) and
approved for cabling by the Fermilab Subcontract Administrator.

The strand awaiting cable fabrication shall be identified, protected,
and handled in a manner to prevent degradation or damage.

Some strand specifications are summarized in the following and in Table
1 (for reference).

1.  Critical current. The strands for the inner layer shall have a
    minimum critical current of 378 A, measured at 7 T and 4.22 K. The
    strands for the outer layer shall have a minimum critical current of
    185 A, measured at 7 T and 4.22 K. The critical current will be
    determined according to a criterion of ρ=10^-14^ Ωm, based on the
    strand cross section area and with the applied magnetic field
    perpendicular to the strand axis.

2.  Copper to superconductor ratio. The copper to superconductor ratio
    shall be (1.3±0.1):1 for the inner layer strand and (1.8±0.1):1 for
    the outer layer strand.

3.  Strand diameter. The strand for the inner layer shall have a
    diameter of 0.808 ± 0.0025 mm. The strand for the outer layer shall
    have a diameter of 0.648 ± 0.0025 mm.

4.  Surface condition. The strand surface shall be free of all surface
    defects, slivers, folds, laminations, dirt, copper fines, or
    inclusions. No NbTi filaments shall be visible at 10x magnification
    under a lighting level of at least 1076 lux.

5.  Strand twist pitch. The strands for the cables for the BTeV C0-IR
    quads shall be twisted so that the filaments follow the opposite
    rotation as the cable lay direction. The inner layer strand twist
    pitch at final size shall be (13 ±1.5) mm. The outer layer strand
    twist pitch at final size shall be (13 ±1.5) mm.

6.  Residual Resistance Ratio (RRR). The strands for inner and outer
    cable shall have a minimum RRR value of 70.

7.  The strand shall survive a sharp bend test, performed in accordance
    with specification 5500-ES-371009 (inner strand) or 5500-ES-371010
    (outer strand) without any sign of cracking at the outside surface
    of the sharp bend visible at 5x magnification under a lighting level
    of at least 1076 lux. Filament damage in excess of 1% of the design
    total number of filaments is cause for rejection.

    Table 1. Strand mechanical and electrical specifications

  ----------------------- ------ ------ ------- ---------- ----------- --------- ------- ---------- ----------- ---------
  Parameter               Unit          Inner                                    Outer                          
                                        cable                                    cable                          

                                        Value              Tolerance             Value              Tolerance   

  Diameter                       mm             0.808                  ± 0.0025          0.648                  ± 0.0025

  Cu/SC ratio                                   1.3 : 1                ± 0.1             1.8 : 1                ± 0.1

  Surface coating                               None                   \-                None                   \-

  Anneal                                        None                   \-                None                   \-

  Minimum critical               A              378                    \-                185                    \-
  current (at 4.22 K, 7                                                                                         
  T)                                                                                                            

  Minimum RRR                                   70                                       70                     

  Twist direction                               Left                                     Right                  

  Twist pitch                    mm             13                     ± 1.5             13                     ± 1.5
  ----------------------- ------ ------ ------- ---------- ----------- --------- ------- ---------- ----------- ---------

## 3.2 Technical requirements for cable {#technical-requirements-for-cable .unnumbered}

Figure 1 shows the cable size parameters and Table 2 shows the cable
mechanical and electrical parameters.

### 3.2.1 Mechanical properties {#mechanical-properties .unnumbered}

1.  Cable size, strand number, cable transposition pitch, and lay
    direction are specified in Table 2. The cross sections of the inner
    and outer cable are shown in drawing numbers 5520-MA-439043 and
    5520-MA-439044, respectively. The method for determining that the
    cable dimensions comply with the requirements are described in
    section 3.3.2 and Appendix I of this document. The cable
    mid-thickness is measured under a pressure of 5 kPsi (34.48 MPa).

> If the cable has a \"right lay\" pitch the strands should be spiraled
> in the same direction as right handed screw thread. The converse is
> true for a left lay direction.

2.  The residual twist shall be less than 40 degree for the inner cable
    and less than 30 degree for the outer cable. The test should be
    performed according to Appendix II.

3.  The cable shall pass tests of bending and mechanical stability
    performed according to Appendix II.

### 3.2.2 Electrical properties {#electrical-properties .unnumbered}

Critical current at 7 T, 4.22 K must be higher than 14.0 kA and 8.5 kA
for inner and outer cables, respectively. The conductors for inner and
outer cable shall have a minimum residual resistance ratio (RRR) value
of 70. The cable electrical properties are also described in Table 2.
The methods used to measure the electrical properties are described in
Appendix III and IV.

![](media/image3.wmf)

Figure 1 The cable size parameters.

Table 2. Cable mechanical and electrical specifications

<table style="width:100%;">
<colgroup>
<col style="width: 32%" />
<col style="width: 0%" />
<col style="width: 9%" />
<col style="width: 0%" />
<col style="width: 13%" />
<col style="width: 0%" />
<col style="width: 13%" />
<col style="width: 0%" />
<col style="width: 13%" />
<col style="width: 0%" />
<col style="width: 16%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="2" rowspan="2">Parameter</td>
<td colspan="2" rowspan="2">Unit</td>
<td colspan="4">Inner cable</td>
<td colspan="3">Outer cable</td>
</tr>
<tr class="even">
<td colspan="2">Value</td>
<td colspan="2">Tolerance</td>
<td colspan="2">Value</td>
<td>Tolerance</td>
</tr>
<tr class="odd">
<td>Number of strands</td>
<td colspan="2"></td>
<td colspan="2">37</td>
<td colspan="2">-</td>
<td colspan="2">46</td>
<td colspan="2">-</td>
</tr>
<tr class="even">
<td>Cable width</td>
<td colspan="2">mm</td>
<td colspan="2">15.40</td>
<td colspan="2">-0.02/+0</td>
<td colspan="2">15.40</td>
<td colspan="2">-0.025/+0.005</td>
</tr>
<tr class="odd">
<td>Minor edge</td>
<td colspan="2">mm</td>
<td colspan="2">1.320</td>
<td colspan="2"></td>
<td colspan="2">1.051</td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td>Cable Mid-thickness at 5 kPsi</td>
<td colspan="2">mm</td>
<td colspan="2">1.465</td>
<td colspan="2">± 0.006</td>
<td colspan="2">1.146</td>
<td colspan="2">± 0.006</td>
</tr>
<tr class="odd">
<td>Major edge</td>
<td colspan="2">mm</td>
<td colspan="2">1.610</td>
<td colspan="2"></td>
<td colspan="2">1.241</td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td>Keystone angle</td>
<td colspan="2">degree</td>
<td colspan="2">1.079</td>
<td colspan="2">± 0.05</td>
<td colspan="2">0.707</td>
<td colspan="2">± 0.05</td>
</tr>
<tr class="odd">
<td>Transposition length</td>
<td colspan="2">mm</td>
<td colspan="2">114</td>
<td colspan="2">± 5</td>
<td colspan="2">102</td>
<td colspan="2">± 5</td>
</tr>
<tr class="even">
<td>Lay direction</td>
<td colspan="2"></td>
<td colspan="2">Right</td>
<td colspan="2">-</td>
<td colspan="2">Left</td>
<td colspan="2">-</td>
</tr>
<tr class="odd">
<td><p>Minimum critical current</p>
<p>(at 4.22 K, 7T)</p></td>
<td colspan="2">kA</td>
<td colspan="2">14.0</td>
<td colspan="2">-</td>
<td colspan="2">8.5</td>
<td colspan="2">-</td>
</tr>
<tr class="even">
<td>Residual resistance ratio</td>
<td colspan="2"></td>
<td colspan="2">≥ 70</td>
<td colspan="2"></td>
<td colspan="2">≥ 70</td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td>Residual twist</td>
<td colspan="2">degree</td>
<td colspan="2">&lt; 40</td>
<td colspan="2"></td>
<td colspan="2">&lt; 30</td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td>Minimum bending radius</td>
<td colspan="2">mm</td>
<td colspan="2">7</td>
<td colspan="2"></td>
<td colspan="2">15</td>
<td colspan="2"></td>
</tr>
</tbody>
</table>

## 3.3 Processing {#processing .unnumbered}

### 3.3.1 Cable manufacturing {#cable-manufacturing .unnumbered}

The strands must be cabled on a high quality, fully controlled cabling
machine, The Vendor must provide evidence that the proposed cabling
machine is capable of fulfilling the stringent quality requirements of
BTeV inner and outer cables. A Cabling Measuring Machine (CMM) should be
installed on line with the cabling machine. The tension on the strands
and on the cable during cabling must be measured and kept constant over
the production.

### 3.3.2 Cable dimensions {#cable-dimensions .unnumbered}

The cable mid-thickness values given in Table 2 for a transverse
pressure of 5 kPsi (34.48 MPa) are the nominal values of each cable
mid-thickness. The mid-thickness of each cable at a pressure of 5 kPsi
is verified by measuring the height of 10 samples (15 cm long) of each
cable stacked with alternated positions in a ten-stack measuring
fixture, the design of which, will be provided by Fermilab to the
Vendor. The ten-stack measurement shall be performed at the beginning of
each cabling run, to adjust the cable mid-thickness on the cabling
machine. The cable width, keystone angle and the mid-thickness must be
measured at 20 MPa during manufacturing and recorded at least every 3 m
by a Cabling Measuring Machine (CMM). Further resizing shall not be
accepted by Fermilab. The ten-stack measurements will be correlated to
the values measured on the CMM during the cable manufacturing. The exact
protocol for on-line dimensional measurements and their reporting must
be agreed between the Fermilab Subcontract Administrator and the bidder
before the contract is signed. Appendix I describes the calibration
procedure currently foreseen for the measurement of the cable
dimensions.

### 3.3.3 Identification {#identification .unnumbered}

Each piece of strand and cable in the cable fabrication process shall be
identified by a unique number code. Strand identification shall be
traceable to the final cable serial number. All cable fabrication
material, processing, inspection, tests, and delivery records shall be
traceable and retrievable to either strand or cable code numbers.

### 3.3.4 Cable Map {#cable-map .unnumbered}

The cable manufacturer shall supply a cable map giving the serial number
of each reel of strand used in the cable. A copy of the cable map should
be shipped with the cable.

### 3.3.5 Cable production lengths  {#cable-production-lengths .unnumbered}

The minimum unit length of cable is 536 m for the inner cable and 608 m
for the outer cable (after cutting all samples required for tests). A
cable production length is a continuous length of cable, which is longer
than the minimum unit length with allowance for sample cutting. The
maximum deliverable unit length for the inner and for the outer cable is
specified in Section 5.

### 3.3.6 Strand Welds  {#strand-welds .unnumbered}

No cold welds are allowed in any production length of cable. Cold welds
used in setup must be clearly marked, and position of the cold welds
must be listed in the production report. These cold welds must be
removed before the cable is shipped to Fermilab.

### 3.3.7 Cable surface condition {#cable-surface-condition .unnumbered}

The cable surface must be thoroughly clean and free from oil, metallic
particles or residue. The cable shall be cleaned with Abzol VG cleaner,
or alternative cleaner approved by the Fermilab Subcontract
Administrator. The cable must be free of roughness, slivers and burrs.

### 3.3.8 Crossover or broken strands {#crossover-or-broken-strands .unnumbered}

There can be no crossovers of strands or broken strands in the cable

### 3.3.9 Sharp edges {#sharp-edges .unnumbered}

The cable should have no sharp edges, as specified in Appendix V. The
cable manufacturer shall take a digital photograph, with a magnification
of 50x, of the cable thin edge at the beginning of each cabling run.
This photo will be part of the quality control documentation and a
digital copy should be provided to the Fermilab Subcontract
Administrator.

###  Degradation during cabling

The cabling degradation, measured as specified in Appendix VI, should
not exceed 5% for any strand. The cable manufacturer should measure at
least three extracted strands per cable production length.

###  Annealing

There should be no annealing of the cable, and the strands to be used in
the cable should not receive any annealing below 3.6 mm diameter.

###  Reels/Spools

The cable must be spooled with a radius larger than or equal to 177 mm.
The spools must be constructed to prevent damage to the cable during
spooling and unspooling. The spools shall be boxed to prevent damage in
shipment. They should be stacked and shipped with the spool flanges
maintained in a vertical orientation (axis horizontal) in order to
prevent the cable from settling on the spool.

###  Spooling requirements 

The cable must be wound on the spool so that there are no crossovers of
the cable layers. Filler cord shall be used at the edges of the cable
layers as required so that the cable will be adequately supported over
the whole wide face and will lie flat. Only one production length of
cable shall be placed on each spool. The cable will be wound onto a
spool in the following manner: As an observer is looking at the
collecting spool, if the spool is rotating clockwise, then the thick
edge of the cable should be facing the observer.

#  {#section-1 .unnumbered}

# 4 QUALITY ASSURANCE AND MANUFACTURING PLAN {#quality-assurance-and-manufacturing-plan .unnumbered}

Prior to the contract being signed, the Vendor shall submit to the
Fermilab Subcontract Administrator, for his/her approval, a documented
Quality Assurance Plan, which fulfills all requirements described in the
present specification. The Vendor shall also submit to the Fermilab
Subcontract Administrator, for its approval, a detailed description of
the test procedures and the model test certificates, which he proposes
to use.

## 4.1 Quality Control Plan {#quality-control-plan .unnumbered}

The cable manufacturer is responsible for performing the inspections and
the tests defined in Table 3 (with the exception of cable critical
current and RRR), for the preparation and maintenance of resultant data
and for the storage of all tested samples until end of the contract. At
the end of the contract all samples shall be sent to Fermilab. The cable
manufacturer shall label all samples used for tests and shall identify
their position within the cable length from which they were taken.

Table 3. Finished cable acceptance inspection/test

+------------------+------------+---------+----------------+----------+
| Characteristic   | R          | Test    | Frequency      | Test     |
|                  | equirement | Sample  |                | method   |
|                  | value      |         |                |          |
+------------------+------------+---------+----------------+----------+
| Cable            | Table 2    | Con     |                |          |
| mid-thickness    |            | tinuous |                |          |
|                  |            | meas    |                |          |
|                  |            | urement |                |          |
|                  |            | with a  |                |          |
|                  |            | CMM at  |                |          |
|                  |            | 5kPsi   |                |          |
|                  |            | (34.48  |                |          |
|                  |            | MPa)    |                |          |
|                  |            | and     |                |          |
|                  |            | o       |                |          |
|                  |            | ff-line |                |          |
|                  |            | check   |                |          |
|                  |            | of      |                |          |
|                  |            | mid-th  |                |          |
|                  |            | ickness |                |          |
|                  |            | with    |                |          |
|                  |            | te      |                |          |
|                  |            | n-stack |                |          |
|                  |            | me      |                |          |
|                  |            | asuring |                |          |
|                  |            | f       |                |          |
|                  |            | ixture; |                |          |
|                  |            | see     |                |          |
|                  |            | 3.3.2   |                |          |
|                  |            | and     |                |          |
|                  |            | A       |                |          |
|                  |            | ppendix |                |          |
|                  |            | I for   |                |          |
|                  |            | details |                |          |
+------------------+------------+---------+----------------+----------+
| Cable width      | Table 2    |         |                |          |
+------------------+------------+---------+----------------+----------+
| Cable keystone   | Table 2    |         |                |          |
| angle            |            |         |                |          |
+------------------+------------+---------+----------------+----------+
| Cable lay        | Table 2    | Vendor  |                |          |
| direction        |            | Quality |                |          |
|                  |            | Control |                |          |
|                  |            | Plan    |                |          |
+------------------+------------+---------+----------------+----------+
| Cable            | Table 2    | Vendor  |                |          |
| transposition    |            | Quality |                |          |
| length           |            | Control |                |          |
|                  |            | Plan    |                |          |
+------------------+------------+---------+----------------+----------+
| Bend test        | No damage  | A       | Beginning and  | Appendix |
|                  |            | ppendix | end of each    | II       |
|                  | \<1%       | II      | production     |          |
|                  | broken     |         | length         |          |
|                  | filam.     |         |                |          |
+------------------+------------+---------+----------------+----------+
| Mechanical       | No strands | A       | Beginning and  | Appendix |
| stability        | out of the | ppendix | end of each    | II       |
|                  | cable      | II      | production     |          |
|                  |            |         | length         |          |
+------------------+------------+---------+----------------+----------+
| Residual twist   | See        | 1 m     | Beginning and  | Appendix |
|                  | 3.2.1.2    |         | end of each    | II       |
|                  |            |         | production     |          |
|                  |            |         | length         |          |
+------------------+------------+---------+----------------+----------+
| Surface          | See 3.3.7  | 100% of |                | Visual   |
| condition        |            | cable   |                | test     |
+------------------+------------+---------+----------------+----------+
| Crossovers or    | None       | 100% of |                | Visual   |
| broken strands   |            | cable   |                | test     |
+------------------+------------+---------+----------------+----------+
| Sharp edges      | See 3.3.9  | See     | Beginning of   | See      |
|                  |            | 3.3.9   | each           | 3.3.9    |
|                  |            |         | production     |          |
|                  |            |         | length         |          |
+------------------+------------+---------+----------------+----------+
| Cabling          | \< 5 %     | Ex      | Minimum of 3   | Appendix |
| degradation      |            | tracted | samples per    | VI       |
|                  |            | strands | cable prod.    |          |
|                  |            |         | length         |          |
+------------------+------------+---------+----------------+----------+
| Cable critical   | Table 2    | 2 m     | Beginning and  | Appendix |
| current          |            |         | end of each    | III-IV   |
|                  |            |         | production     |          |
| and RRR          |            |         | length         |          |
+------------------+------------+---------+----------------+----------+

##  {#section-2 .unnumbered}

## 4.2 Manufacturing plan {#manufacturing-plan .unnumbered}

Prior to contract being signed the Vendor shall establish and make
available to the Fermilab Subcontract Administrator, for his/her
information, a manufacturing plan describing the process and all
tooling, machines and equipment. The implementation of any change to the
manufacturing plan after the beginning of manufacturing is subject to
prior written approval by the Fermilab Subcontract Administrator.

## 4.3 Certificate of compliance {#certificate-of-compliance .unnumbered}

The cable manufacturer shall provide a written statement certifying
compliance with the requirements of this specification with each product
shipment, together with a completed copy of all documentation including
all test results and cable map. This documentation shall include all
documents requested by this specification, and by the associated
specifications for the strands (5500-ES-371009 or 5500-ES-371010), for
NbTi bars and rods (5500-ES-371015), and for Nb barrier (5500-ES-371016)
showing that all materials used in the deliverable cable are in
compliance with the above specifications. All documentation is to be
provided in an electronic form (format should be approved by the
Fermilab Subcontract Administrator) also. This documentation shall be
provided to the Fermilab Subcontract Administrator after the completion
of all tests, measurements, and inspections. This documentation shall be
sent prior to, or at the absolute latest, concurrently with the cable.

### 4.3.1 Nonconforming material  {#nonconforming-material .unnumbered}

Finished cable failing to meet the requirements of Table 2 shall be
identified by condition and segregated from conforming material.
Material shall remain on hold pending notification to, and disposition
by the Fermilab Subcontract Administrator.

## 4.4 Submission of test samples  {#submission-of-test-samples .unnumbered}

Before shipping a cable spool to Fermilab, the Vendor must deliver to
Fermilab a 2-m long sample taken from each end of the cable production
length on that spool, and a 4-m long sample taken from one end of the
cable production length on that spool. Sample identification must
include the mention "pre-shipment test samples", the data specified in
Appendix VII section 1.2, and the position with respect to the cable
during cabling (start or end of cabling run). These samples must be
delivered to Fermilab [as soon as possible after cable
manufacturing]{.underline} and before cable shipment. The samples must
be accompanied by the results of mechanical measurements made during
cable fabrication and by a copy of the cable strand map. These samples
will be used by Fermilab to verify the mechanical and electrical
characteristics of the cable before the approval for the delivery of
each cable spool. Fermilab will send to Brookhaven National Laboratory,
for performing the cable critical current and RRR measurement, the 2-m
long samples from the ends of each production length.

# 5 SHIPPING AND IDENTIFICATION REQUIREMENT {#shipping-and-identification-requirement .unnumbered}

The maximum deliverable unit length per spool is 2400 m for the inner
cable and 2800 m for the outer cable. If a cable production length is
longer than the maximum deliverable unit length, then the cable
manufacturer shall contact the Fermilab Subcontract Administrator in
order to be told how to divide the production length into deliverable
lengths. Each deliverable length shall be packaged and shipped as a
single unit. Requirements for packaging, shipping and identification are
specified in Appendix VII.

# Appendix I - Procedure for the Measurement of Cable Dimensions {#appendix-i---procedure-for-the-measurement-of-cable-dimensions .unnumbered}

## I.1 Cable dimensions {#i.1-cable-dimensions .unnumbered}

The Turks-head adjustments to produce the cable with the specified
mid-thickness, have to be made using the results of the ten-stack
measurement at 5 kPsi (34.48 MPa) as the reference value. The cable
mid-thickness measured by the Cable Measuring Machine (CMM) are to be
considered relative measurements to maintain the cable mid-thickness
within the required tolerances.

The initial measurements of the cable width and keystone angle have to
be made with the CMM calibrated using a certified reference standard
gauge before each cable-manufacturing run.

## I.2 Calibration of the Cable Measuring Machine and gauge checks  {#i.2-calibration-of-the-cable-measuring-machine-and-gauge-checks .unnumbered}

At the beginning of each cable-manufacturing run the CMM is to be
calibrated using a certified, flat, reference gauge. This initial
calibration is further checked using keystone angle gauges certified by
Fermilab. The following test sequence is required to check the CMM
calibration.

-   Make a minimum of two measurements with the flat reference gauge

-   Make a minimum of five measurements with the nominal keystone angle
    gauge

-   Make a minimum of five measurements with the maximum keystone angle
    gauge

The angular measurements given by the CMM are expected to be within ±
0.01º of the keystone angle gauge.

## I.3 Checks at the beginning of the run  {#i.3-checks-at-the-beginning-of-the-run .unnumbered}

At the beginning of each cable manufacturing run the cable mid-thickness
value at 5 kPsi (34.48 MPa) is to be measured using the ten-stack
fixture. Cable samples used for off-line tests of the cable dimensional
and mechanical requirements ("hub" cable samples in the following) are
to be taken just after having made the final Turks-head adjustments,
giving the cable within the specified dimensional tolerance limits. At
the start of production of the 2-m long "hub" cable sample for the
ten-stack measurements, the CMM mid-thickness measurements are to be
made at intervals of 30 cm. The average value of these measurements will
be correlated to the mid-thickness value determined on the "hub" cable
sample with the ten-stack fixture. Before starting the cabling run, a
photo of the thin edge of the "hub" cable with a magnification of 50x
will be taken and inspected to ensure the absence of sharp edges.

## I.4 Checks at the end of the run  {#i.4-checks-at-the-end-of-the-run .unnumbered}

Normally, at the end of the cable-manufacturing run, the cable
mid-thickness should be stable within 2 μm. The Vendor should ensure
that this is the case. The cable mid-thickness value is to be checked,
off-line, by a ten-stack measurement. During production of the 2-m long
cable sample at the end of the cable-manufacturing run, the CMM
mid-thickness measurements are to be made at intervals of 30 cm. The
average value of these measurements will be correlated to the
mid-thickness value determined with the ten-stack fixture. At the end of
the cable manufacturing run the CMM calibration is to be checked by
carrying out a minimum of two measurements against the flat reference
gauge.

# Appendix II - Mechanical Tests {#appendix-ii---mechanical-tests .unnumbered}

-   **Residual twist**: The twist is measured by suspending a 11.34 Kg
    (25 lb.) weight from a 1m length of cable and measuring the
    difference in the angle between the cable surfaces at the top and
    the bottom of the sample.

-   **Bend test**: The purpose of this test is to verify the absence of
    cracks and fractures after bending in order to ensure that the cable
    is suitable for coil winding. A cable sample 200-mm long is bent
    over a rod (the rod diameter for each cable is shown in Table 2)
    while applying a 32-Kg tensile load. The cable must keep its
    coherence after bending. The bent cable will be examined under a
    microscope with a magnification of at least 50x to determine if any
    strands are cracked or fractured near the cable edges. Subsequently,
    the bent area of the sample will be etched in nitric acid and
    examined for possible filament damage. Cables showing more than 1%
    broken filaments will not be accepted.

-   **Mechanical stability test**: The cable sample for this test should
    be 135-cm long and should have both ends soldered (soldered part
    should be between 1 and 2 cm in length). The sample should be bent
    in order to make a coil of 26-cm diameter as shown in Figure II.1.
    The overlapping parts of the sample should be taped together at
    point A. No mandrel or any other support should be used during
    sample bending. The sample should be examined for strands popping
    out of the cable. A strand is defined "out of the cable" when, in
    any point, it is out of registration with the nominal cable surface
    by 40% or more of its diameter. In order to pass this test the cable
    should preserve its shape and no strands should be out of the cable
    after bending.

Figure II.1: Sample for cable stability test.

# Appendix III - Cable Critical Current Determination {#appendix-iii---cable-critical-current-determination .unnumbered}

## III.1 Introduction {#iii.1-introduction .unnumbered}

The sections below describe the test method used at Brookhaven National
Laboratory (BNL) to determine transport critical currents of meter long
cable samples. These procedures have proven suitable for production
testing. Fermilab will provide the samples.

The critical current of a cable, I~c~, is less than the sum of the
individual strand values as there is invariably some degradation during
the fabrication of the cable. This is expressed as follows:

$\text{D = }1 - \left( \frac{I_{c}}{\sum_{}^{}I_{\text{cw}}} \right)$

where Σ I~cw~ = sum of the Ic's of the strands in the cable. An
allowance for degradation, is D \< 0.05 (=5%).

The critical current is a function of temperature, T, and magnetic
field, B. It is necessary to convert (or \"correct\") short sample test
results obtained at particular values of T and B, to values
corresponding to a standard temperature and field. The steps in this
conversion are as follows:

a)  Obtain raw data for several applied fields: I~ct~, critical current
    at bath temperature, T, and applied field, B~a~. For BTeV quadrupole
    cable, the applied fields are 6.7, 7.0, 7.3 T for inner cables, and
    5.6, 6.3, 7.0 T for outer cable.

b)  Calculate the peak field, B: the sum of the applied field and the
    self-field, due to the measurement current.

c)  Convert I~ct~ at field B to I~c~, the value corresponding to
    reference temperature T~ref~.

d)  Plot I~c~ vs. B and calculate I~c~ at the reference field from a
    linear fit to the data.

The calculations used in the above steps are described in detail below..

## III.2 Definition of Critical Current {#iii.2-definition-of-critical-current .unnumbered}

The critical current is a property of the reversible portion of the V-I
curve. It is defined as that current for which

$VI\text{ = }\frac{\text{10}^{- \text{14}}}{\left( \frac{{N\pi d}^{2}}{4} \right)}$

where V = voltage drop per m, I = current in amps N = no. of strands in
cable d = strand diameter in m. The shape of the V-I curve is of the
form V = constant × *I^n^*^+1^. (Note that n is defined from the
equation ρ = constant × *I^n^* ). The quantity *n* is routinely measured
as required by the specifications.

## III.3 Sample Mounting {#iii.3-sample-mounting .unnumbered}

The samples are mounted in a compression fixture, which is illustrated
in Figure III.1. The test arrangement involves four bare cable samples.
As these are keystoned, (i.e., they are trapezoidal in cross-section),
care is taken to alternate thick and thin edges so that pairs of
conductors present parallel surfaces to the clamping faces. As indicated
in Figure III.1 there are a series of separators: 0.76 mm. thick G-10
strips which carry electrical instrumentation described below, and 0.25
mm. thick Mylar strips which insulate adjacent samples of the upper and
lower cable pairs.

Compression is applied by tightening 9.53 mm (3/8 in.) bolts. A torque
of 53 N-m (240 inch-pounds) is used to tighten the bolts. This produces
a clamping pressure of 54± 7 MPa for the 15 mm wide BTEV cables at room
temperature. The standard configuration for quality control testing is
the perpendicular one, i.e., the applied dipole field is perpendicular
to the sample faces. Rotation of the sample fixture relative to the
magnet is prevented by means of a locating key on the fixture and a
slotted plate at the bottom of the magnet.

Figure III.2 shows schematically how the cables are connected to each
other and to the gas cooled leads. The connections are made using
ordinary soft solder over a 15 cm. length. A typical joint resistance is
about 10^-9^ ohm. The samples are excited in pairs, either A-B, or C-D.

![](media/image4.png){width="3.8222222222222224in"
height="2.0416666666666665in"}

Figure III.1 Mechanical assembly of 2 pairs of cable.

![](media/image5.wmf){width="3.897222222222222in"
height="1.854861111111111in"}

Figure III.2 Electrical Wiring Schematic.

## III.4 Electrical Instrumentation {#iii.4-electrical-instrumentation .unnumbered}

Primary instrumentation consists of the following:

-   Five voltage taps and thin foil heater element for each sample.
    These are contained on the G-10 strips shown in Figure III.2. The
    voltage taps work by the pressure contact of a copper wire across
    the width of the sample. The heater element is a strip of stainless
    steel foil, 0.013 mm. thick x 3 mm. x 6 mm, which is located in a
    shallow well formed in the G-10 strip.

-   Hazemeyer DCCT secondary current standard.

-   Digital voltmeters, 6-1/2 digit, 0.1 μV sensitivity.

-   Nicolet 12 bit, 4 channel digital oscilloscope.

-   Two calibrated carbon resistor thermometers, located at each end of
    the magnet.

-   Isolation preamplifiers, 1 mV noise level.

Secondary instrumentation consists of the following:

-   Quench current protection circuits for the magnet, the gas-cooled
    leads, and the samples.

-   DC power supplies for persistent switch, and sample heater element.

-   Pulse power supply for sample heater element.

## III.5 Measurement Procedure {#iii.5-measurement-procedure .unnumbered}

The cable samples are energized in pairs, either A-B or C-D in Figure
III.2 and the V-I curves are determined simultaneously for each member
of the bifilar pair. In quality control tests of production cables, the
match between samples is close enough that I~c~\'s can usually be
determined for all four samples. In the rest of this section we shall
describe the procedure for testing one cable only, it being understood
that a pair of samples, or all four, are under simultaneous test.

The measurements are made with the helium bath level above the upper
sample and well above the top of the dipole magnet. The magnet field is
set to a desired value and locked in with the persistent switch. The
standard arrangement is such that the field is oriented perpendicular to
the cable face.

The relative direction of the current flow and of the magnet field is
very important for reasons which will be discussed below. Therefore, the
polarity of the power supply connections is carefully checked. Before
the V-I curve is measured the sample is trained. This is done by ramping
the current until a quench occurs. For relatively high Cu/SC ratio
cables, one quench is usually sufficient to reach the plateau value of
I~q~.

Voltage-current readings are taken with a current ramp of \~200A/s.
On-line the V-I data are converted to log ρ - log I data and fitted by a
straight line. This gives the 10^-14^ ohm · m current and the n-value
(the slope of the log-log plot). However off-line a separate analytical
technique is used for calculating I~ct~ and n-value. The results of this
analysis are reported: B~a~, T, I~ct~ I~q~, n, where B~a~ is the applied
field, and I~q~ is the quench current or a lower limit of it. This
procedure is repeated for each of the four cables at several fields in
the vicinity of the specification field.

## III.6 Temperature Calculation {#iii.6-temperature-calculation .unnumbered}

Calculations of the critical currents at temperatures other than that at
which I~c~ is measured are made using the same procedure as that for
wires. The specification temperature is usually 4.222 K, that of boiling
helium at standard atmospheric pressure. The bath temperature is
recorded with the aid of cryogenic thermometry with a precision of ±
0.002K (2 mK). A \"linear T\" type of correction is applied for
temperatures different from 4.222 K:

$\frac{I_{c}}{I_{\text{ct}}} = \frac{T - 4\text{.}\text{222}}{T_{c} - T_{\text{bath}}}$

$T_{c}(B)\text{ = 9}\text{.}2\left\lbrack \text{1 - }\frac{B}{\text{14}\text{.}5} \right\rbrack^{0\text{.}\text{59}}$

where T~c~(B) is the transition temperature at the specified magnetic
field. I~ct~ is the current measured at temperature T, and I~c~ is the
critical current at the specification temperature. The field B is not
just the applied field but that which takes into account the field
produced by the cables as explained below.

## III.7 Magnetic Field Correction[^1]  {#iii.7-magnetic-field-correction .unnumbered}

The magnetic field is the sum of the applied field produced by the
dipole magnet and the self-field produced by the measuring current. The
following assumptions give results that are self-consistent for a wide
variety of geometry and which give reliable predictions of magnet
behavior.

a)  The critical current of the sample is determined by the peak
    magnetic field. This depends, of course, on the orientation of the
    applied field and the direction of the sample current.

b)  The sample current is distributed uniformly over, and normal to, the
    area of the trapezoid that encloses the cable cross-section.

c)  The geometry is accurately reproducible; this is a matter of care in
    assembly.

With the dipole field perpendicular to the wide face of the sample, the
peak field occurs at a point on the surface of the sample where the
self-field and the applied field are very nearly parallel; that is, they
are simply additive. For the standard test configuration, the self-field
correction can be written:

$\text{B } = \text{ B}_{\text{peak}} = B_{a} + c \times I_{\text{ct}}$

where B~a~ = dipole field and c = geometric constant. Below is given the
value of c for BTeV cable, for B~a~ perpendicular to the sample, and for
the standard BNL test geometry in which the bifilar samples are
separated by 0.25 mm

Self-field constant, c, T/kA, for BTeV Inner Cable: 0.02480

Self-field constant, c, T/kA, for BTeV Outer Cable: 0.02530

## III.8 Critical Current of the Thin Edge: {#iii.8-critical-current-of-the-thin-edge .unnumbered}

The thin edge of a keystone-shaped cable is of interest. The bifilar
sample test arrangement with applied field perpendicular has the
characteristic feature that the peak fields occur at diagonally opposite
points, at the two thin edges (c.f. Figure III.3). the quality control
test determines the critical current for the thin edge; i.e. the field
and current direction are oriented as in Figure III.3.

![](media/image6.wmf){width="4.236111111111111in"
height="1.636111111111111in"}

Figure III.3 Contours of constant field magnitude for perpendicular
applied field of 6T and current of 10kA. The peak field of 6.4T occurs
at the thin edge of the cable.

# Appendix IV - Cable R(295) and RRR Determination {#appendix-iv---cable-r295-and-rrr-determination .unnumbered}

As in the case of wires, the cable resistance at 295 K and that at 10 K
is determined using the same set-up used for Ic determination. The
residual resistance ratio, RRR, is defined to be R(295)/R(10). R(295) is
measured with an accuracy of 0.5%; R(10) is measured with an accuracy of
2%.

The room temperature measurement is made using a DC current of 1 A, and
voltage contacts 61 cm apart (see Figure III.2). A thermocouple device
of 0.1^0^C accuracy is used to determine the ambient temperature.
Normally occurring room temperature variations produce significant
variations in the measured resistance. Designating this resistance as
R~m~ and the ambient temperature as t(^0^C), the resistance at the
reference temperature of 295 K is calculated as follows:

$R(\text{295}) = \frac{R_{m}}{1 + 0\text{.}\text{0039}\left( t - \text{22} \right)}$

The effect of the Nb-Ti is negligible for the purpose of this
correction.

The low temperature measurement is a dynamic one, made by inducing a
superconducting-normal state quench while the cable is carrying current.
Referring to Figure III.2, a quench is triggered in Cable A, for
example, by means of heater HA. The resulting waveform observed at
nearby voltage taps, A2-A3 or A3-A4, consists of three parts: a
superconducting state baseline voltage, a linear ramp voltage
corresponding to the passage of the superconducting-normal interface
between the voltage taps, and a slowly increasing signal characteristic
of the normal state resistance. The latter increases in time due to
normal state heating. However, at first the voltage is almost constant
due to the residual resistance characteristic of the copper. Thus, there
is a kink in the voltage waveform at the beginning and at the end of the
linear ramp portion. The voltage difference between these two points
equals the current times the residual resistance of the section of cable
between the voltage taps. The resistance per centimeter is determined
for two pairs of taps (A2-A3 and A3-A4 in the above illustration) and
averaged. The taps are relatively close to the heater in order to
minimize the effect of current fall-off which results from the increase
of normal state resistance as the quench propagates. Routinely the
resistance in zero field is measured.

# Appendix V - Cable Sharp Edge  {#appendix-v---cable-sharp-edge .unnumbered}

The cable should have no sharp edges. An edge is defined as sharp when
the two flat surfaces of a strand, at a cable edge (see Figure V.1), are
closer than 0.2 mm (inner cable) or 0.15 mm (outer cable). The cable
manufacturer shall take a digital photograph, with a magnification of
50x, of the cable thin edge at the beginning of each cabling run. This
photo will be part of the quality control documentation and a digital
copy should be provided to the Fermilab Subcontract Administrator.

![](media/image7.png){width="3.916535433070866in"
height="3.8125984251968505in"}

Figure V.1: Cable edge specification

# Appendix VI - Measurement of Degradation During Cabling {#appendix-vi---measurement-of-degradation-during-cabling .unnumbered}

Before shipping a cable production length to Fermilab, the Vendor should
measure the critical currents of a minimum of three (3) strands
extracted from that cable, and compare them with the critical currents
of the same strands before cabling. The cabling degradation should not
exceed 5%. To have a sufficient number of measurements for statistics,
Fermilab requires that critical current measurement be performed on at
least three extracted strands per cable production length. The strands
should be selected in such a way that each billet entering each cable
production length is tested. Short samples should be taken from one end
of each cabling run, directly on the cabling machine where the
identification is still possible. The cabling degradation will be
computed by making critical current measurements at 6, 7 and 8 T and
corrected to the reference temperature of 4.22 K as described in
Appendix III. The above data must be reported to the Fermilab
Subcontract Administrator before cable shipment.

# Appendix VII - Packaging and shipping of Superconducting Cable {#appendix-vii---packaging-and-shipping-of-superconducting-cable .unnumbered}

This appendix establishes the minimum requirements for the packaging and
shipping of superconducting NbTi Cable. This cable will be used in the
manufacture of the BTeV C0 IR quadrupole magnets.

The seller shall provide written request to the Fermilab Subcontract
Administrator for any exceptions or deviations to the technical
requirements prior to proceeding with implementation. Such
implementation shall require written authorization by the Fermilab
Subcontract Administrator.

**1.0 REQUIREMENTS**

1.1 [Spools]{.underline}

The cable shall be shipped on spools, which have an inner radius larger
than or equal to 177 mm, a 38.1 mm (1-1/2 inch) diameter center hole, a
maximum outer diameter of 914 mm, and a maximum outside width of 457 mm.
Rope filler is to be used as needed to ensure that cable lays flat on
the reel so as to avoid any distortion to the cable caused by spooling,
or by storage or transit. The spools shall be constructed to prevent
damage to the cable during spooling, unspooling and shipment.

1.2 [Marking/Identification Requirement]{.underline}

Spools and exterior packaging shall be identified with the following
information in the order shown:

> BTeV C0 IR Quadrupole Magnet superconducting cable
>
> Type (Inner or Outer) [I or O]{.underline}
>
> Strand manufacturer \_\_\_\_\_\_
>
> Fermilab P.O. No. \_\_\_\_\_\_
>
> Reel ID. \_\_\_\_\_\_
>
> Drawing No. \_\_\_\_\_\_
>
> Length (m) \_\_\_\_\_\_
>
> Weight (kg) \_\_\_\_\_\_
>
> Cable Map No. \_\_\_\_\_\_
>
> Date of Manufacture \_\_\_\_\_\_
>
> Name of Manufacturer \_\_\_\_\_\_

The Reel ID in the list should be in format of 'BTeV-I-S-Cxxxx.' 'I'
means inner cable. In the case of outer cable this will be 'O.' The
following 'S' indicates the strand manufacturer (use the first letter of
the name of the strand manufacturer). The following 'C' indicates the
cable manufacturer (use the first letter of the name of the cable
manufacturer). The last field shows the four digits of the cable ID
number.

1.3 [Packaging]{.underline}

The cable should be packed in a manner that will protect it from any
kind of damage that could occur in shipping from mishandling or exposure
to the elements. As a minimum, the following is required:

1.3.1 The cable on the reel shall be wrapped with a layer of cardboard
followed by a layer of sheet metal adequate to avoid any damage that
could happen during shipping or while in storage.

1.3.2 Wrap cable with a layer of new, clean polyethylene having a
minimum thickness of 1.5 mm (.06 inch). Hold with plastic banding
straps.

1.3.3 Bag spool in 0.13 mm (5 mil.) polyethylene to protect the cable
from dirt. Place a desiccant material in the bag to protect from
moisture.

1.3.4 Production documentation and the cable certification documentation
package should be placed in a water tight envelope and attached to the
flange of the spool.

1.4 [Shipping]{.underline}

The cable spool shall be shipped as a palletized unit.

1.4.1 Place the spool on a pallet custom made to the size of the spool,
with the spool flanges maintained in a vertical orientation (axis
horizontal) in order to prevent the cable from settling on the spool.
(Custom pallets are reusable.)

1.4.2 Attach the spool to the pallet through the horizontal axis of the
spool with banding material (palletized unit).

1.4.3 Cover the entire package with a 16 mm (5/8 inch) plywood crate
banded to the pallet holding the plywood cover in place.

**2.0 QUALITY ASSURANCE**

2.1 [Inspection and Compliance]{.underline}

The seller is responsible for the performance of all necessary
inspections to assure conformance with section 1.

2.1.1 The inspection performed to meet the requirements of this
specification shall be incorporated into the seller\'s quality system.

2.1.2 Each spool of cable shall be treated as a separate lot for the
purpose of packaging inspections. Every lot of material must be examined
prior to shipment for all of the characteristics mentioned in section 1
of this appendix (requirements).

2.2 [Acceptance of Material]{.underline}

Fermilab reserves the right to reject any material not conforming to the
requirements of this specification.

[^1]: ^2^ " The effect of self field on the critical current
    determination of multifilamentary superconductors", M.Garber et.al.,
    IEEE Trans. on Magnetics, Vol25, p1940 (1989)