Monitoring Vacuum Quality Using A
Residual Gas Analyzer
Julio BarbosaLawrence Livermore National Labs
CFAO Intern 2004
Today’s High Tech Industry
Today’s High Tech Industry• As technology advances the requiredmanufacturing processes becomeincreasingly complex
• Manufacturing must be carried out in strictly controlled environments
• Clean rooms and vacuum systemsare required
The VLOC Project
•VLOC will require operation in a cleanhigh vacuum
•High vacuum doesn’t mean clean vacuum
•Measuring minute amounts of matteris a non-trivial task
Residual Gas Analyzers
How An RGA Works
= A mass spectrometer
• Ion Source+
• Mass Filter+
• Ion Detector
The Test Chamber
Testing Materials
Materials tested:
•O-rings•Wax sealant•Oil from fingerprints
First test conducted with anempty chamber for a baseline
1.825E-143.26E-142.527E-139.42E-15A, Argon40
7.776E-143.52E-132.17467E-131.1178E-12O2, Oxygen32
3.448E-123.01E-127.25867E-123.763E-12N2, CO, Nitrogen, Carbon Monoxide 28
1.251E-131.48E-132.0396E-128.40867E-14C2H3, Vinyl Radical27
1.308E-131.32E-139.26267E-135.92367E-14C2H2, Acetylene26
2.53E-112.21E-114.52767E-114.37733E-11H2O, Water18
7.547E-126.59E-121.29233E-119.50E-12OH, NH3, Water, Ammonia17
1.262E-121.14E-122.013E-122.36933E-12CH4, Methane16
8.936E-141.17E-136.25167E-131.12E-13CH3, Methyl Radical15
2.023E-131.59E-134.10667E-133.54E-13C, Carbon12
2.623E-112.70E-115.63567E-114.17E-11H2, Hydrogen2
Fingerprint(Amps)
Wax(Amps)
w/ O-Ring(Amps)
Baseline(Amps)
Atomic Mass Number
Taking DataMaterial Comparison
0.00E+00
1.00E-11
2.00E-11
3.00E-11
4.00E-11
5.00E-11
2 12 15 16 17 18 26 27 28 32 40Atomic Mass Unit (AMU)
Curr
ent (
Amps
)
BaselineO-ringWaxFingerprint
Rates of Decay
0.00E+00
2.00E-11
4.00E-11
6.00E-11
8.00E-11
1.00E-10
1.20E-10
1.40E-10
0 17 35 52 69 87 104 121
Time (minutes)
Cur
rent
(Am
ps)
MASS( 2 )MASS( 4 )MASS( 8 )MASS( 12 )MASS( 16 )MASS( 18 )MASS( 20 )MASS( 26 )MASS( 28 )MASS( 30 )MASS( 32 )MASS( 34 )MASS( 40 )MASS( 42 )MASS( 44 )MASS( 46 )MASS( 69 )MASS( 71 )
Applying The DataRates of Evacuation
This project is supported by a Research Experiences for Undergraduates (REU) supplement to the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under a cooperative agreement No. AST-9876783.
Acknowledgements
•Center For Adaptive Optics•LLNL Staff
Rick LevesqueJay AyersShannon WardNhan Nguyen