Graham Beck 6 Feb Thermal QC Options for the Bare Stave/Petal Core This is about thermal QC, i.e. during production. Aims Primary: Verify that the core functions thermally i.e. will remove module heat. Secondary: Check mechanical integrity (thermal signature of stave construction faults ). QC tests -will be made on every stave / a fraction / none? … depending on yield and experience. -should cause minimal damage/degradation (e.g. non-contact measurements). - should be made with ~ identical systems, that users are happy with, across sites. Possible Tests: Please suggest additions / alternatives / details (e.g. T ranges) ! 1)Thermal Performance: Fluid through pipe (e.g. CO 2 at operating T) + Surface thermal load (to mimic modules). Measure surface T distribution. 2)Thermal Cycling: e.g. -40C to +40C, followed by thermal/mechanical tests (tbd). - from this morning’s Freiburg summary (Sergio): -35/-40C to T g (+30/50?) 1)Thermal Shock: Robustness against Power and/or Coolant ON  OFF + accidents!

Graham Beck 6 Feb Issues: Expect flow rate LOW for 2mm id pipe (BNL to check full length sample) >5C T rise around loop. [FD flow calcns ok to ~ 20%. htc ≈ 4000 W/m 2 K ] !! Worse performance for equivalent chiller in Europe (50Hz cf 60Hz). Precision IR measurements of absolute T unlikely: camera systematic errors (~ 4C vignetting, narcissus – also known to QMUL). Thermal load poorly defined - but expect very similar to module load. Providing flow is acceptable, GOOD for comparative tests + finding localised faults. (Note BNL core pressure test does not check foam-pipe joint). Thermal Performance Test. What we have so far: BNL Chiller circulating LIQUID (hfe7100 ) at -35C. 6bar? Thermal load from ambient (box flushed with N 2 ) Surface T from scanned IR camera: – NON-contact! - Clearly can detect missing glue between facing and foam (built-in faults, ≥20mm long).

Graham Beck 6 Feb WARM liquid: A potentially quick, first stage QC of thermal performance. e.g. hfe7100 at +40C (chiller). Q transfer to ambient ≈ 30% module heat. Simple set-up: no N 2 box, easy IR view Useful so far, flowing water (eventually must replace by hfe due to corrosion concern). Stitch-up of ~ 12 IR thermograms (each distorted due to ~20° viewing angle) US Stave250 (foam sealed with BN/Hysol, CGL joint) looked uniform UK Plank7 : unreliable joint between foam and pipe or facing? (3C wobbles, confirmed by TCs. Not seen on reverse face) camera was eventually tilted!

Graham Beck 6 Feb Alternatives: BNL-like Chiller + hfe7100 (in cooling pipe). In principle much faster (if well insulated). T Range: -35C to +50C. (lower T possible, see later). TRACI Evaporative CO 2 (if adequate control) : -40 to about +15C only. For higher T need heating elements too. Thermal Shock not investigated, but expect possible with either CO 2 or Chilled liquid. Thermal Cycling (Freiburg summary (Sergio): environmental chamber ok for petals, difficult for staves) QMUL “Coffin”: custom built environmental chamber. Cooling by liquid N 2 dewar boil-off (77K). Switched (noisy). Heaters. Fanned circulation. Large volume (stack several staves). Convective exchange with surface => ±50°C cycle takes 1 hour. Doesn’t rely on cooling tube => useful for bus tapes etc pre-assembly (but a cooling tube based chamber could be faster?).

Graham Beck 6 Feb Liquid hfe7100 Bi-phase CO2 Lytron Chiller (AMS)TRACI Blow-off Stave T range (C, approx.) -35 * => => +15 Pressure [bar] 6 10 – 50 Programmable ? Yes Yes (tbc) No ! (e.g. for Thermal Cycling) (but need heaters?) Other advantages Off-the-shelf, Moderate P. CO 2 – as ATLAS Other problems Low flow rate (add aux. Build effort ! Build effort ! pump: HighP/LowT spec!) User friendly? Need bottle bank? Safety issues? Capital cost * £19k (no hfe7100 warranty) £50k ? (initially) £5k £38k (-80/+50C, hfe7100) Capability can usually be extended by investing £££s + technical expertise (where available). TRACI capabilities to be discussed with Lukasz Zwalinski (ff. feedback from today). What is minimal acceptable thermal QC? What is best combination of test apparatus using Liquid (chiller), Gas (N 2 cycling) and bi-phase (CO 2 ) ? Need a plan – solution will depend on QC requirements (need agreement on these)

6 Example of a non-production QC setup: UK Thermomechanical Stave (2010) + Blow-off CO 2. Destructive: glued dummy modules + ntcs. Graham Beck 6 Feb 2015

BNL BN-Hysol samples for thermal conductivity measurement. (Centrifuged to de-gas. Room temperature cure...) BN: ZYP, PT140, PT180, Goodfellows × 10, 20, 30% by weight. - LBNL: Thermal Diffusivity apparatus. - QMUL: TIMTower - a ±5% measurement? On-going effort to ensure understand IR systematics (background, response..) Need more equal  Ts sample vs tower: Replace Cu (385) by Pb (35.3) W/mK) Graham Beck 6 Feb T vs height

8 Laser surface height measurement ( two of slides from Dave Lynn, Jan 2015) -Detects built-in missing glue faults (plus maybe an unintentional one!...) -working on speeding up + reducing noise spikes (IR, for comparison)

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