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LHQ Traces Analysis and Recommendations for Heater Design

Detailed analysis of LHQ traces for current status, including voltage tap positions, heater layout, and issues found during fabrication. Recommendations provided for heater trace design modifications, Kapton thickness decision, material suggestions, and future trace proposals for LHQ project.

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LHQ Traces Analysis and Recommendations for Heater Design

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  1. HQ / LHQ Traces M. Marchevsky, A. Salehi & D. Cheng LBNL 02/07/2013

  2. LHQ traces: current status • Voltage tap positions and heater layout (L2) have been determined • Layer 2 negative and trial traces have been produced • Hipot of the latest L2 trace passed 1500 V

  3. LHQ voltage taps

  4. LHQ Layer 2 trace layout “LQ-style” heater R. Hafalia

  5. Resistance / power estimate r316 SS = 75.4 10-6 Ohm cm L= 100.8 mm W= 44.8 mm L= 44.46 mm W=9.0 mm 24x + R2 25x RH= R1 R1= 75.4 10-6(10.8/(4.48*25*10-4) = 0.072 Ohm R2= 75.4 10-6 ( (2.405 + 3.14*0.65) / (0.9*25*10-4) = 0.1489 Ohm S2 = (2.405 +3.14*0.65)*0.9 = 4.00 cm2 RH= 1.8 + 3.56 = 5.36 Ohm P1 /A = 464/4.00 = 116 W/cm2 P1 = (300/5.36)2 x 0.1485 = 464 W

  6. Fabricated LHQ trace 50 micron Kapton

  7. Problems found Point indentations in the stainless steel (seem to do not perforate Kapton) • Also, many smaller sized indentations are visible, likely caused by non-uniform rollers • Trace is very “wavy”, hard to press down flat • It is very easy to crease, unlike the current HQ traces; likely due to a softer (annealed?) stainless steel used

  8. Hipot results High leakage current was present. However, the trace passed hipot at 1500 V at 10 mA limit 1 mA 2 mA 10 mA (trip voltage)     (trip voltage)      (trip voltage)Top            516501500 passedMiddle335391500 passedBottom       356221500 passed

  9. LHQ heater traces: decisions to be made - Do we plan to have a heater for the Layer 1? Trace with Vtaps only has been modeled already (Ray), but fabrication of the negative should be initiated. - Are we OK with the current Layer 2 trace design or do we want to modify it? Proposals were made to implement spot heater and additional voltage taps around it to do quench propagation studies in LHQ. Do we want to go forward with these plans? - Do we agree on Kapton thickness of 50 micron? It appears that thinner Kapton is hard to handle for trace manufacturers; thicker material may cause too long

  10. Heater/Instrumentation Trace Material • The three layers: • 25 µm Stainless steel • 304, tempered • 13 µm Adhesive • Modified epoxy cross-linked system • 25 µm Polyimide • Apical AV • Hipot tests are performed with this configuration • Additional 50 µmKapton is attached prior to installation in a coil

  11. HQ (Made at LBNL)

  12. Future Heater/Instrumentation Trace Proposals • The three layers: • 25 µm Stainless steel • 316 annealed or tempered • 13 µm Adhesive • Modified epoxy cross-linked system • 25-50 µm Polyimide • Apical AV • Will eliminate the additional layers • But may not protect against any perforations/pinholes in material at processing

  13. LHQ Traces ( Only Outer Layer, 3.2 meter) • Currently, there is a size limitation that prevents fabrication at LBNL • Two unsuccessful attempt with outside vendors • Flexible Circuit Company • First trace was received with many defects (unusable) • Abandoned future traces with this company • Mapson Engineering • First unit has some wrinkled and metal lifting (316 SS and 25µm Kapton) • Second unit vendor experienced epoxy removal issues (304 SS and 50µm Kapton), but this is a material issue, not fabrication issue • Due back at LBNL by 3/8/2013

  14. LHQ Traces ( Only Outer Layer, 3.2 meter) • Building up the long trace fabrication capabilities limitation at LBNL • Outside vendor has produced the negative artwork for etching mask • Currently modifying handling trays to able to process long traces • Will try to qualify long coil traces on 3/11/2013

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