1. John Amann – ILC Mechanical Engineering 11/13/06
Non-Evaporable Getters (NEGs) in the ILC BDS 11/10/06 Meeting with SAES Getters
John Amann – ILC Mechanical Engineering
11/13/06

2. Meeting with SAES Getters:
Michael Ferris (US Applications Engineer)
Paolo Manini (Business Area Manager)
Mauro Pivi (SLAC)
John Amann (SLAC)

3. NEGs at CERN NEG used for pumping since 1950’s, sintered or strips.
At CERN deposited micron NEG film (Ti30V40Zr30) directly on chamber.
Reduces gas pressure.
Acts like conductance free distributed pump.
Barrier for gases, reduces thermal out-gassing.
Other interesting features – low secondary electron yield, low
gas de-sorption rates from charged particle, photon bombardment.
Ideal for very narrow, conductance limited chambers.

4. The Coating Process Can be applied to Al, Cu, SS.
Magnetron sputtering process.
Can be applied to Al, Cu, SS.
Uses krypton gas plasma = less entrapment in film
than argon.
Chamber must fit inside 45cm diameter magnet coil.
Maximum chamber lengths of ~6.5m, limited by facility.
Longer sections can be coated and welded
together (Al, SS).
1 micron on 2m section takes 1 day to coat.
Thickness of coating can vary over irregular surfaces,
profiles.
Areas to be uncoated can be masked. Difficult to achieve
sharp edge boundary.
Electrically conductive, not as good as Al however.

5. Operation and Performance of NEGs
  To activate the NEG material it must be heated at ~200°C for up to a day.
Chambers which need to be activated would require wrapping with heat tape.
 After initial activation, the material should not need activation again for life, barring
a vent/leak.
An alternative to coating whole chambers, the CF mounted NEG pump.

6. Uncertainties/Concerns
Durability of NEG material under high SR power of ILC beam.
Overall long term durability of coating, will it flake off resulting in reduced
pumping efficiency of chamber?
They (SAES) seem interested in investigating the SR durability.
PEPII experience, works well until heated by SR. Must be careful with
placement for ILC.
SAES production capacity and logistics, if at Fermi possible US facility.

7. Recommendations
Consider replacing some ion pumps with CF mounted NEG pumps.
400l/s NEG pump ~$3000 vs. 400l/s diode ion pump ~$6000.
PS should be about same order.
Very compact and lightweight, can mount in any orientation.
Pump cartridge can be replaced quickly if damaged.
Activation heater is integrated with TC on CF, chambers would need
heat tapes, etc.
Does not pump noble gases, so can not eliminate all ion pumps.

8. Recommendations Investigate use of NEG films at ILC BDS.
Test durability/performance in ILC-like environment (SR, etc.).
Obtain cost estimate for coating typical chamber sections
(BNL chamber ~$10k for .25m x 5m section).
Develop pumping model for coated chambers. Need to understand
what we are getting for the $$.
Think about where it might be used (near IP to reduce backgrounds).
Is it cost effective? Will it last the life of the ILC?