AVS 57th International Symposium & Exhibition
    Vacuum Technology Tuesday Sessions
       Session VT+MS-TuM

Paper VT+MS-TuM5
Novel Instrument Capable of Efficient Gas Exchange to Remove Gas-phase Contamination in Complex Volumes Without Purging or High Vacuum

Tuesday, October 19, 2010, 9:20 am, Room Laguna

Session: Outgassing, Contamination Control, and Process Modeling
Presenter: J. Brown, Sandia National Laboratories
Authors: J. Brown, Sandia National Laboratories
J. Hochrein, Sandia National Laboratories
S. Thornberg, Sandia National Laboratories
Correspondent: Click to Email
Countless systems used in research and in industry contain complex assemblies that are sealed in some type of enclosure, meant to isolate them from the harsh operating environment of the open atmosphere and to maintain a pristine internal atmosphere. Unfortunately, the internal atmosphere of any sealed component or system is, in the long-term, only as clean as the materials sealed within its enclosure. Over time, moisture or other volatile contaminants initially trapped in the materials can begin to evolve and accumulate with potentially detrimental effects on the functionality of the component. This problem can be extremely difficult to address, depending on the physical and mechanical constraints of the particular system. Recently, an instrument was developed at Sandia National Laboratories that can “clean” the internal atmosphere of a critical optical component that cannot be subjected to conventional conditioning methods (such as N2/Ar purge, high-vacuum pumpdown, etc.). By using multiple pressurization and evacuation cycles tightly controlled within a narrow ±2 psig window, the instrument fully and efficiently exchanges the liters of moisture- and contamination-laden internal gas of the component with clean, dry N2. This process is repeated as moisture from the internal materials diffuses back into the gas phase until, over time, the source of the moisture is depleted. This instrument has been successful in reducing the equilibrium gas-phase moisture levels in the optical component from the thousands of PPMv (parts per million by volume) to single-digit PPMv. This instrument, called the “Automated Pressure Cycler,” will be discussed in detail.