PRODUCTION COST ISSUES FOR COSINE THETA AND COMMON COIL MAGNETS

Peter Wanderer, BNL

Vlhc MAGNET WORKSHOP

FERMILAB --- MAY, 2000

Compare cosine theta, common coil:

processes

components

new ideas for cost-reduction r&d?

+--------------------------+-------------------+-----------------------+
| ##### S                  | ##### NbTi        | **Nb3Sn or HTS        |
| UPERCONDUCTOR PROPERTIES |                   | (prereacted)**        |
+--------------------------+-------------------+-----------------------+
| ## Cost                  | # Cheap           | #### Expensive        |
+--------------------------+-------------------+-----------------------+
| Cable shape (precise)    | # Keystoned       | #### Rectangular      |
+--------------------------+-------------------+-----------------------+
| Minimum bend radius      | # \< 1 cm         | # \~ 3 cm             |
+--------------------------+-------------------+-----------------------+
| Winding tension          | # Medium to high  | # Medium              |
+--------------------------+-------------------+-----------------------+
| Turn-to-turn insulation  | Kapton -- 1 mil   | ### Glass cloth-      |
|                          | delicate & robust | --delicate and robust |
|                          | to \~ 140 MPa     |                       |
+--------------------------+-------------------+-----------------------+
| Apply turn-to-turn       | Barberpole wrap   | ### Sock, weav        |
| insulation               |                   | e, or barberpole wrap |
+--------------------------+-------------------+-----------------------+

Cost: New Nb~3~Sn R&D effort (multilab, multivendor)

##  Separate copper stabilizer from superconducting wire

Bend radius: common coil magnets

+-----------------------+-----------------------+-----------------------+
| ##### COIL DESIGN     | ##### Cosine Theta    | #####                 |
|                       |                       | Common Coil Racetrack |
+-----------------------+-----------------------+-----------------------+
| Peak Field/Central    | Highest               | Similar in optimized  |
| Field                 |                       | design                |
+-----------------------+-----------------------+-----------------------+
| Field Quality         | 2D wedges, thick 3D   | 2D rectangles, thick  |
| (systematic)          | end spacers           | 2D end spacers (+     |
|                       |                       | auxiliary coils?)     |
+-----------------------+-----------------------+-----------------------+

Field quality: Start with large 2D coils.

Study tradeoffs:

complexity of auxiliary coils,

separate trim coils,

accelerator physics systematic f.q. tolerances

+-----------------------+-----------------------+-----------------------+
| **COIL MANUFACTURE**  | **Cosine Theta (3D)** | **Racetrack (2D)**    |
+-----------------------+-----------------------+-----------------------+
| Coil Winder           | 3D (rotates winding   | ## 2D                 |
| (automatic)           | mandrel)              |                       |
+-----------------------+-----------------------+-----------------------+
| Straight section      | ## Trapezoidal wedges | ##                    |
| (precise wedges)      |                       | ## Rectangular wedges |
+-----------------------+-----------------------+-----------------------+
| Ends                  | Many 3D separators,   | ###                   |
|                       | inserted by hand      | # A few 2D separators |
+-----------------------+-----------------------+-----------------------+
| Leads                 | # Solder t            | # Different solder t  |
|                       | o NbTi expansion loop | o NbTi expansion loop |
+-----------------------+-----------------------+-----------------------+

+-----------------------+-----------------------+-----------------------+
| **COIL MFGR.          | **Cosine Theta (3D)** | **Racetrack (2D)**    |
| (cont.)**             |                       |                       |
+-----------------------+-----------------------+-----------------------+
| Coil sizing fixture   | # 3D                  | 2D                    |
|                       |                       |                       |
|                       | # 70 MPa              | 0.1 MPa               |
|                       |                       |                       |
|                       | # precise             | precise               |
|                       |                       |                       |
|                       | # heated              | vacuum impreg.        |
|                       |                       |                       |
|                       | # complex insert      | 2D insert             |
+-----------------------+-----------------------+-----------------------+
| Conductor position    | # \~ 25 m to 50 m     | Little data           |
| random variation      |                       |                       |
+-----------------------+-----------------------+-----------------------+

\*\* Common coil conductor position: make multiple (short) coils and
magnets, nominally identical, measure field quality

+-------------------------+--------------------+-----------------------+
| **COIL ASSEMBLY**       | ##### Cosine Theta | ##### Common coil     |
+-------------------------+--------------------+-----------------------+
| "Degree of difficulty"  | 6                  | 3                     |
+-------------------------+--------------------+-----------------------+
| Field Quality focus     | Top-bottom coil    | Left-right coil       |
|                         | matching           | matching (little      |
|                         |                    | data)                 |
+-------------------------+--------------------+-----------------------+
| Preload in straight     | Preload Lorentz    | Low appears to be ok  |
| section                 | force              |                       |
+-------------------------+--------------------+-----------------------+
| Axial preload           | Thick endplates    | #### Nominal          |
+-------------------------+--------------------+-----------------------+

Field Quality: left-right matching calculations, trial assemblies

Preload: R&D fixturing that allows preload to be varied cheaply.

+-----------------------+-----------------------+-----------------------+
| **COIL ASSEMBLY       | ##### Cosine Theta    | ##### Common coil     |
| (cont.)**             |                       |                       |
+-----------------------+-----------------------+-----------------------+
| Assembly press        | Massive, precise      | Nominal (precise)     |
|                       | dimensions            |                       |
+-----------------------+-----------------------+-----------------------+
| Coil contact parts    | Precise, complex      | Precise support       |
| (laminations)         | collars (die cost)    | plates (laminated?)   |
+-----------------------+-----------------------+-----------------------+
| Ground plane          | Folded kapton         | Kapton with many      |
| insulation            |                       | fewer folds           |
+-----------------------+-----------------------+-----------------------+

Coil contact parts:

laminated vs. nonlaminated designs for common coil.

+-----------------------+-----------------------+-----------------------+
| **YOKE (laminated)**  | ##### Cosine Theta    | ##### Common coil     |
+-----------------------+-----------------------+-----------------------+
| Shape                 | Approximately round   | Racetrack interior,   |
|                       | interior, exterior    | round or rectangular  |
|                       |                       | exterior              |
+-----------------------+-----------------------+-----------------------+
| Amount of material    | Lots, especially      | ###### Less           |
|                       | 1-in-1                |                       |
+-----------------------+-----------------------+-----------------------+
| Configuration         | 1-in-1 vs 2-in-1      | 2-in-1                |
+-----------------------+-----------------------+-----------------------+