SAES Project Combination of NEG module and sputter

SAES Project: Combination of NEG module and sputter ion pump VSC Seminar 16/04/2010 S. Meunier TE-VSC

Objectives • To compare base pressure between a combination of NEG module and ion pump and only for ion pump, for a bake out vacuum system • Compare base pressure for different bake-out duration for these two configurations • Compare base pressure for a combination of NEG module and different ion pump (different pumping speed of ion pump) VSC Seminar 16/04/2010 S. Meunier TE-VSC

SAES NEG Module Capaci. Torr-D 2000 MK 5 • • • Alloy type: St 172 Getter Alloy Mass : 225 g Getter Surface : 1900 cm² Pumping speed (l/s): 2000 l/s (H 2) and 1000 l/s (CO) VSC Seminar 16/04/2010 S. Meunier TE-VSC

NEG Module Cartridge: The Capacitor cartridges are configured in the form of sintered porous disks of St 172. These sintered porous bodies are arranged in the cartridge structure in a way to optimize speed and capacity performances. Pump Body: The optional pump body is a simple double flanged nipple Heater: The heater of the D 2000 consists of a tantalum wire spiral wound on an alumina element supported by a stainless steel rod. This heater is part of the pump cartridge structure. Thermocouple: The thermocouple is a K type electrically insulated within an alumina tube. It is assembled on the support flange and connected to the electrical connector with compensated contact terminations. VSC Seminar 16/04/2010 S. Meunier TE-VSC

Ion pumps selected for this project: Star. Cell 400 l/s and Star. Cell 200 l/s Star. Cell 75 l/s and Star. Cell 40 l/s VSC Seminar 16/04/2010 S. Meunier TE-VSC

Project description Systematic evaluation of NEG module and ion pump combinations: ultimate vacuum pressure and test for shorter bake out duration. Task list: • • • Construction of a dedicated vacuum system Pumping speed measurement of each ion pump Pumping speed measurement of the NEG module Calibration of the system and base pressure Influence of baking time at 150°C for 5 different values of pumping speed with and whithout NEG module VSC Seminar 16/04/2010 S. Meunier TE-VSC

NEG Module Pumping speed measurement • Pumping speed measurement of the NEG module with a Fischer-Mommsen dome : • Injection of H 2 and CO gas SNEG (l/s) = C (l/s) (αΔP 1/ΔP 2 -1) – S turbo(l/s) With the conductance C : C= 34. 4 l/s for H 2 and C= 9. 19 l/s for CO With the calibration SVT 1/SVT 2, α = 0. 85 for H 2 and α = 1 for CO ΔP = P - P initiale P= P x SN 2/SH 2 pour H 2 et P= P x S N 2 /S CO Sensibility S N 2 S H 2 S CO SVT 1 43 16. 35 36. 64 SVT 2 34 16. 42 28. 97 VSC Seminar 16/04/2010 S. Meunier TE-VSC

NEG Module Pumping speed measurement S (l/s) for H 2 S (l/s) for CO NEG activation 45 min at 450°C 1990 l/s 936 l/s NEG activation 24 h at 450°C 2201 l/s 1530 l/s SAES data: 2000 l/s (H 2) and 1000 l/s (CO) for 45 min at 450°C activation VSC Seminar 16/04/2010 S. Meunier TE-VSC

Vacuum test stand VSC Seminar 16/04/2010 S. Meunier TE-VSC

Vacuum test stand VSC Seminar 16/04/2010 S. Meunier TE-VSC

Influence of the bake out duration • Bake out duration: 24 hours, 12 hours, 6 hours and 3 hours • Bake out température : 250°C for stainless steel vacuum chambers 250°C gate valve DN 150 CF 250°C NEG module 300°C ion pump 350°C VGI gauges and residual gas analyser 140°C injection valve 200°C valve on the turbo pump • Ion pump: 400 l/s VSC Seminar 16/04/2010 S. Meunier TE-VSC

Test procedure(1) • Venting of the system 15 hours (except NEG module which stay under vacuum) • Pumping of the system+ leak detection+ open gate valve to pump NEG module • Start bake out (300°C) • At the end of the maximum temperature level, reduction of the temperature at 180°C for gas analyser and B. A. G gauges and 150°C for the rest of the vacuum system • Flash of the ion pump • Degasing of the B. A. G gauges 45 min at 50 m. A • Degasing of the R. G. A 45 min at 20 m. A VSC Seminar 16/04/2010 S. Meunier TE-VSC

Test procedure (2) • At the end of the degasing, activation of the NEG module 45 min at 450°C • Degasing 5 min and start gauges and gas analyser • Start ion pump • Close valve on the turbo pump and injection valve • Stop bake-out • 24 hours after the bake out stop, note pressure of the two BAG gauges and save a scan • Close the gate valve, wait 30 min and note the pressures and save a scan. VSC Seminar 16/04/2010 S. Meunier TE-VSC

Results of the base pressure without NEG module Base pressure with 400 l/s ion pump Bake out duration hours P 1 (torr) P 2(torr) 24 h at 300°C 1, 5. 10 -10 1, 6. 10 -10 12 h at 300°C 1, 4. 10 -10 1, 5. 10 -10 6 h at 300°C 1, 5. 10 -10 3 h at 300°C 1, 6. 10 -10 1, 5. 10 -10 VSC Seminar 16/04/2010 S. Meunier TE-VSC

Results of the base pressure with NEG module activated Base pressure with combination of NEG module and 400 l/s ion pump Bake out duration hours P 1 (torr) P 2 (torr) 24 h at 300°C 0, 8. 10 -11 1, 0. 10 -11 12 h at 300°C 0, 4. 10 -11 1, 0. 10 -11 6 h at 300°C 1, 1. 10 -11 1, 0. 10 -11 3 h at 300°C 1, 1. 10 -11 VSC Seminar 16/04/2010 S. Meunier TE-VSC

Mass scan after bake-out VSC Seminar 16/04/2010 S. Meunier TE-VSC

Influence of the bake-out temperature • Bake out duration: 6 hours • Bake out température : 150°C for stainless steel vacuum chambers 140°C gate valve DN 150 CF 150°C NEG module 150°C ion pump 350°C VGI gauges and residual gas analyser 140°C injection valve 150°C valve on the turbo pump • Ion pump: 400 l/s - The same procedure as before was applied. we only reduced the temperature of the bake-out to 150°C except for the gauges and gas analyser VSC Seminar 16/04/2010 S. Meunier TE-VSC

Influence of the bake-out temperature Bake out temperature P 1 (torr) P 2 (torr) with NEG activated without NEG activated 300°C 6 hours 1, 1. 10 -11 1, 0. 10 -11 1, 5. 10 -10 150°C 6 hours 3, 1. 10 -11 1, 4. 10 -11 2, 0. 10 -10 1, 5. 10 -10 VSC Seminar 16/04/2010 S. Meunier TE-VSC

First conclusions 1. We have the same pressure for all the different bake-out duration: P= 1, 5. 10 -10 torr only with ion pump (gate valve closed) P= 1, 5. 10 -11 torr with NEG module and ion pump 2. We have the same base pressure at 150°C and 300°C for a 6 hours bake-out duration with and without NEG module 3. We have the same base pressure for a 24 hours bake-out duration at 300°C and for a 6 hours bake-out at 150°C with and without NEG module. It is possible to reduce duration and temperature of bake-out to achieve the same base pressure. VSC Seminar 16/04/2010 S. Meunier TE-VSC

Influence of other parameters Bake out 150°C, 6 hours P 1 (torr) with NEG activated P 2 (torr) with NEG activated P 1 (torr) without NEG activated P 2 (torr) without NEG activated NEG under vacuum during air venting, TLabo=28°C 3, 1. 10 -11 1, 4. 10 -11 2, 0. 10 -10 1, 5. 10 -10 NEG air venting 3, 5. 10 -11 1, 6. 10 -11 1, 5. 10 -10 1, 2. 10 -10 NEG under vacuum during air venting, T Labo =20°C 3, 6. 10 -11 1, 5. 10 -10 1, 1. 10 -10 4, 9. 10 -11 2, 5. 10 -11 1, 7. 10 -10 1, 2. 10 -10 NEG activated during all the bake-out duration (6 hours) VSC Seminar 16/04/2010 S. Meunier TE-VSC

Modulation of the gauges • Modulation of the two Bayard-Alpert gauges SVT 1 and SVT 2 Pressure before modulation: P 1= 2, 1. 10 -11 torr P 2= 1, 1. 10 -11 torr After 20 minutes of modulation: • For SVT 1: Pres= 1, 1. 10 -11 torr (high value!) • For SVT 2 : Pres= 3, 2. 10 -12 torr VSC Seminar 16/04/2010 S. Meunier TE-VSC

Modulation of the gauges Problem with SVT 1: leakage current VSC Seminar 16/04/2010 S. Meunier TE-VSC

Outgasing rate of the vacuum system 1. When the gate valve is closed (only ion pump) P= 1, 5. 10 -10 torr Q= P. S= (1, 5. 10 -10 x 100)/0, 45=3, 3. 10 -8 torr. l/s (pour H 2) 2. When the gate is opened (NEG + ion pump)) P= 1, 5. 10 -11 torr Q= P. S= (1, 5. 10 -11 x 2000)/0, 45=6, 4. 10 -8 torr. l/s (pour H 2) Conclusion: The base pressure of this vacuum system is limited by the outgasing of the gate valve. VSC Seminar 16/04/2010 S. Meunier TE-VSC

Base pressure measurement • Remove the gate valve. • Bake-out at 300°C for 24 hours with the same procedure as before. Measure 24 hours after bake-out stop: P 1= no value or 7. 10 -12 torr (without modulation factor) P 2= 3. 10 -12 torr (P 2= 1. 5 10 -11 torr with the gate valve) VSC Seminar 16/04/2010 S. Meunier TE-VSC

Mass scan for base pressure VSC Seminar 16/04/2010 S. Meunier TE-VSC

Next steps • Precise measurement of the pressure of the two gauges for the base pressure. • Calibration of the two gauges and gas analyser using the gas injection line. • Change the 400 l/s for the other smaller ion pumps and compare the measurements. • Continue pumping speed measurement on the Fischer Mommsen dome for the different ion pumps VSC Seminar 16/04/2010 S. Meunier TE-VSC

Thank you for your attention VSC Seminar 16/04/2010 S. Meunier TE-VSC