M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN % Model Outgassing Rate Measurement Model building status Setup Method explanation –Throughput method w/ variable conductance –Rate-of-rise method

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Assembly Status – Shingled Substrate

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Assembly Status – Dummy Silicon Silicon assembly –ROC –Sensor –HDI Almost complete

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Assembly Status Substrate to be modified to fit dummy silicon assemblies

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Test Setup - Chamber Stainless steel 19.5 inches ID 66 inches length

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Test Setup – Vacuum Vessel 3 turbo pumps in parallel Total pumping speed 2550 L/sec Fixed & rotating disk dividing chamber into 2 volumes Rotating disk with different sized holes

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Test Setup – Vacuum Vessel Volume 1 (w/ sample) = 50” length Volume 2 = 16” length RGA

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Test Setup – Variable Conductance Rotate disk to different pumping speeds between volumes 2”, 2”+3”, 6” Largest A~500 cm 2 Blank (no seals between disks)

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Methods to measure gas load Throughput method with variable conductance –Measurements at pressures between & torr –Extrapolate to torr (test can’t reach this) Rate-of-rise method –Cross-check measurements from throughput method

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Throughput method w/ variable conductance For a given orifice size: Q=P 1 S=P 2 S pump &

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Assumptions Q = n d – n a whereQ = outgassing rate n d = desorption rate n a = adsorption rate Outgassing rate is dependent on chamber pressure Decrease pressure, decrease n a, more accurate measure of Q

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Capability of Test Setup When the orifice size changes, what happens to: –P 1 –ratio of sample surface area (~3 m 2 ) to effective area of pumping orifice (S/11.6 L/sec-cm 2 )

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Assumptions in Test Design Constant gas load of 0.01 torr- L/sec (Q is independent of P 1 ) Outgassing rate of test chamber is negligible Flow through orifice is room temperature

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Varying pumping speed d (in) d (cm) A (cm 2 ) C (L/s) S (L/s) P 1 (torr) Ratio Blank ~10 1.0e-330, e e e Large~500 ~5000~ e Ratio = sample surface area (3m 2 ) : effective area of pumping orifice

M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN Rate-of-Rise Method Different than previous rate-of-rise test Use same test chamber Use largest orifice –P 1 settles at steady-state condition Then, change to blank position –Long settling time –Measure outgassing rate at beginning of transient –Use as a cross-check for throughput method