1. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 1 10% Model Outgassing Rate Measurement Model building status Setup Method explanation –Throughput method w/ variable conductance –Rate-of-rise method

2. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 2 Assembly Status – Shingled Substrate

3. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 3 Assembly Status – Dummy Silicon Silicon assembly –ROC –Sensor –HDI Almost complete

4. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 4 Assembly Status Substrate to be modified to fit dummy silicon assemblies

5. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 5 Test Setup - Chamber Stainless steel 19.5 inches ID 66 inches length

6. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 6 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

7. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 7 Test Setup – Vacuum Vessel Volume 1 (w/ sample) = 50” length Volume 2 = 16” length RGA

8. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 8 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)

9. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 9 Methods to measure gas load Throughput method with variable conductance –Measurements at pressures between 10 -3 & 10 -6 torr –Extrapolate to 10 -7 torr (test can’t reach this) Rate-of-rise method –Cross-check measurements from throughput method

10. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 10 Throughput method w/ variable conductance For a given orifice size: Q=P 1 S=P 2 S pump &

11. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 11 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

12. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 12 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 )

13. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 13 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 air @ room temperature

14. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 14 Varying pumping speed d (in) d (cm) A (cm 2 ) C (L/s) S (L/s) P 1 (torr) Ratio Blank ~10 1.0e-330,000 25.0820.3235215 4.7e-5 1600 2+365.9760600 1.7e-5 580 615.2182.021201200 8.3e-6 290 Large~500 ~5000~18005.6e-6 190 Ratio = sample surface area (3m 2 ) : effective area of pumping orifice

15. M. WONGPIXEL MECHANICAL GROUP MEETING 14 JAN 2002 15 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