# Presentation: 499861

## Various Topics for Discussion Today

- Cherrill Spencer
- SLAC & ILC Magnet Systems Group
- LCFOA Magnet Workshop
- 18 October 2006

## Various topics we hope to cover today

- TODAY we are looking for input from magnet manufacturers on
**the setting of standards for the ILC magnet materials and hardware **
**your wisdom on the most accurate cost-estimating procedures for the production of accelerator magnets **
**your preferred magnet procurement process**
**your approximate fabrication capacity**
**anything else you would like to tell us about fabricating accelerator magnets**

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

##                Some Fabrication Standards We Know  Will be Imposed [page 1/2 ]

**Hollow Copper Conductors**
***Quality of Copper***
**The electrical conductivity of the copper will be at least 100% IACS. Alloy will be U.S.A., ASTM C 10200 OF**
**The composition of the copper will be Cu minimum 99.99%, O maximum 0.0005 %.**
***Preparation of the copper*****: will be bright annealed to a deadsoft temper (per ASTM B188), free of surface defects or damage, nicks, cuts and scratches**** **
***Minimum lengths of conductor to order: *****the minimum length of segments of copper conductor ordered must be long enough to wind a single water circuit with ****no internal brazed joints. **
- Coils will be designed so that water circuits’ length are commensurate with continuous lengths that can be procured

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## Hollow conductor issues we have not yet decided upon: want your input

***Shape of conductor : a failure analysis of many operational magnet  failures at SLAC led to conclusion that ROUND hollow conductor (per ASTM B75) would reduce the occurrence of water leaks. ***
***Are you comfortable winding round hollow Cu?***
***Sizes of conductor:  for the magnets where ILC does not specify the coil parameters in detail, we may impose a short list of permissible conductor sizes from which vendor may choose; these sizes would already have dies.***
*For small magnet quantities we might have a pool of ILC Cu conductor available at a copper vendor, so that price per lb is discounted relative to the small quantity you need. ****Can you work with such a system?***

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## Some likely hollow Cu conductor sizes

- Cooling water holes must be at least 3mm in diameter.
- Smallest size:  4.76 mm outside, 3.18 mm diameter hole, .0 1mm corner radius
- Medium size:  6.50 mm outside, 3.10 mm diameter hole, 0.8 mm corner radius
- Large size:      8.50 mm outside, 5.50 mm diameter hole, 1.0 mm corner radius

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## Insulation and Epoxy Topics

**ILC water cooled coils will be vacuum impregnated (called “potted “) rather than made by wet lay-up method. Potting achieves**** better dimensional stability and water resistance. ****The reduction in number of coils shorting out  from nearby water leaks worth the higher cost.**
**Insulation on the conductor will depend on its outer size**
- Size <0.8mm (0.31”) :have Double Dacron Glass (DDG) applied by specialist insulation vendor per NEMA Standard Pub. No. MW1000-1997, section MW-46-C (Double).** **
- Size >0.8mm : magnet vendor will wrap half-lapped plain glass tape with Silane or Volan treatment
**Do you think it is better to put a half-lapped layer of 3M Mylar tape under the glass tape?**

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## A possible potting epoxy, any comments on it?

**SLAC POTTING EPOXY #2 :INFORMATION FOR SLAC’s MODERATELY LOADED COIL POTTING EPOXY** (see separate WORD document for full details)
- Main Components DER332 (epoxy Bisphenyl-A); DER732 (Flexibilizer Resin)
**Additives: **NMA (Hardener); BDMA (Catalyst ) Z6040 (Wetting agent); Cab-o-Sil (Silicon Dioxide);  Alumina Tabular T-64 (NOTE this formula includes the powdery alumina– to enhance radiation resistance)
**ARE YOU USED TO POTTING WITH ALUMINA FILLED EPOXY?**

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

##  Some Fabrication Standards We Know  Will be Imposed [page 2/2]

**If the core is solid steel then hot rolled low carbon steel plate will be used. C1006 or C1008 or C1010.****  For a quadrupole we will ask:**
- 4 quadrants ground on the outside; 4 pieces bolted together and  the 4 poletips & coil pockets EDM’d in the same operation; can achieve 0.005mm reproducibility on the poletips resulting in better coil pocket stability and tolerances.
***Are you able to EDM steel cores?***
**If the core is laminated we will specify a particular electrical steel with a specified pre-treated surface [not yet determined].**
***What do you consider the minimum number of laminations that makes it worthwhile to use lams rather than solid steel?***
***Do you have a favorite electrical steel or favorite surface treatment for lams?***

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## Examples of Magnet Coil Fabrication Specifications we might include in an RFP

- Vendor will prepare tooling drawings and submit a copy of each drawing to ILC for review and future reference.
- Tools and fixtures fabricated by or supplied to the vendor for the fabrication of coils shall be considered the exclusive property of ILC.
- Vendor shall submit in writing an itemized plan of how vendor intends to wind and impregnate the coils.
- A schematic diagram showing all fixtures & tooling utilized in the winding process, together with the above plan, shall be submitted to ILC for approval.
- Approval of these materials & procedures shall not relieve the seller’s responsibility of producing satisfactory magnet coils.
***Would these requirements increase your magnet price?***

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## Magnet interfaces with outside world need to be standardized

- Structure and spatial orientation of power terminals will be specified in detail
**New style power terminals****: **we want to avoid using custom made power terminals which would be different for each magnet and need bolts and washers to attach the power cable lug to the terminal. We are thinking of using *Multi-Contact *plugs and connectors-***do you have any experience with them?***
- Low Conductivity Water (LCW) hoses will be completely specified and
**Fittings that connect hose to conductor**
**Fittings that connect hose to LCW system**
**Maintain electrical isolation**
- Alignment fixtures– will be specified

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## Why do we need to improve the reliability of ILC magnets over existing accelerator magnets?

**MTBF (Mean Time Between Failure): **MTBF is a basic measure of reliability for repairable items.  It can be described as the number of hours that pass before a component, assembly, or system fails.

**MTTR (Mean Time To Repair): **MTTR is the average time required to perform corrective repair on the removable items in a product or system.

**Failure rate = MTBF****-1**** =******

**Availability of N magnets = (Availability of one magnet) ****N**

- Why do we need to improve the reliability of ILC magnets over existing accelerator magnets?

**Expected Downtime in hours = (1-Availability) x Operation hour/year**

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

##            Observations of Magnet Failures at SLAC and other Particle Physics Labs show how the MTBF value can vary depending on time period studied, choice of magnets

- ILC REQUIREMENT FOR AVERAGE MTBF for any single magnet : 20,000,000 hours
- From SLAC 1997-2001 data:  water cooled electromagnet’s average MTBF was **1,150,000** hours. *But– look at a different period and eliminate the worst offenders*:
- Using data from 2002 and eliminating some notoriously failure-prone “DR” magnets (by removing them from the dataset) the measured average MTBF becomes vastly longer:** ****12,000,000** hours. We understand why the DR magnets fail more frequently and would avoid making the same design mistakes in ILC magnets.
- Magnet MTBFs reported by various accelerators vary widely, sometimes because their failures were not carefully counted. Other labs’ magnets have suffered from different problems to SLAC’s. 1 million hours is at the low end of reported MTBFs for water-cooled magnets.
- By any measure the ILC’s magnets have to be designed and fabricated with more care than any other accelerator’s magnets here-to-fore.
- We have to carry out detailed Failure Modes and Effects Analyses (FMEA) to learn how to revise our magnet designs, fabrication  techniques and operating conditions to make more reliable magnets.
***What is your favorite magnet failure story?***

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

##            When we really get to design the ILC magnets we will have to do FMEAs on basic magnet styles

- Failure Mode and Effects Analysis (FMEA) process considers each mode of failure of every component of the system, identifies their causes and ascertains the effects of each failure mode on system operation (**ALL** ILC components should have FMEA done on them).
- The causes of the most severe and likely to occur failures of a standard SLAC water- cooled electromagnet were identified as (a) water leaks and corrosion (b) various assembly errors.
- At SLAC: design changes were made in the conductor, power terminals, core & numbers of items of a water-cooled electromagnet. We have to decide if these changes will be applied to ILC magnets also.
**Prototypes should be made to study how to improve the reliability of failure-prone components, e.g. brazes, power terminals, LCW hoses. **
**VERY IMPORTANT: find ways to reduce repair time. *****How can you help us with this goal?***

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## An example of brazing requirements, page 1/2

- Continued on next slide

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## An example of Brazing requirements, page 2/2

***Do you monitor the temperatures of the conductors when brazing them?***
***Would having to monitor the temperatures noticeably increase your labor costs for the coil fabrication?***

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## Possible procurement methods

- ILC does magnetic design, does top assembly layout drawings and *all* detailed part drawings; provides detailed written fabrication specs.
- ILC does magnetic design, does top assembly layout drawings, completely specifies conductor, pole shape, # water circuits, provides written fab specs, but does NOT provide detailed part drawings
- ILC provides detailed fabrication specs, magnetic parameters, overall mechanical dimensions, required field quality and provides NO drawings at all.
** *****Which method does your company prefer?***

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## Discussion about cost estimating methods

- We are in the middle of making cost estimates of all the ILC magnets, which will be included in the overall cost of the ILC which will be presented to several Governments’ agencies (e.g. DOE) next Spring.
- It is very important that our magnet cost estimates be accurate, so we need to try to match the prices you are likely to charge us.
- The more anyone knows about a magnet style the more precisely one can build up its fabrication cost by estimating the labor hours to do each of the fabrication tasks. But we don’t have time to design each style in much detail, so we are trying other methods.
- E.g. Cost by overall weight of finished magnet   OR

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## Discussion about cost estimating methodscontinued

- Cost by weight of finished coils plus cost by weight of finished core
**i.e. calculate the material cost of a pound of insulated copper (X) and the labor cost of winding & potting a pound of copper (Y); add together : $(X+Y) per lb = $Z per lb**
***Is it necessary to have different Y values for quadrupole coils compared to dipole coils?***
***Does the value of Y remain the same across all weights of coils, or does it vary?***
***Can you also estimate the cost of assembling of core & coils into magnet by overall weight?***

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006

## Cost Reduction Advice

- We need to design magnets that are not un-necessarily costly.
***What advice do you have for us to help us make reliable but not expensive magnets?***

- LCFOA Magnet Workshop:                                         Spencer Standards/Specs discussion

- 18 October 2006