The Measurement of Low Energy Ion Sputtering Yields Utilizing RBS
EMSL Project ID
2263
Abstract
Sputtering, a process by which a target is removed by an impinging ion, has been studied in great detail since the early sixties. Despite this, the need exists for accurate sputtering yield information, experimental and analytic, at low ion energies and heavy ions. For example, there are no sputtering yields found the literature for Mo - Xe system below 100 eV and the values at 100 eV vary as much as a factor of 30. Most work to date has been performed to measure sputtering yields at low ion energies and light ions. Heavy ion sputtering at low ion energies are of importance in xenon ion and Hall thrusters. In these devices, erosion of the thruster's molybdenum ion extraction grids must be known and minimized to assure appropriate mission lifetime. Lifetime tests of ion thrusters (~15,000 hrs long) are extremely expensive. They consume a lot of manpower and large amounts of liquid nitrogen for vacuum facility cooling. Life-tests also have to be run in large vacuum facilities that duplicate space-like conditions, requiring extremely large pumping speed capabilities. The only reliable method of predicting the life -time of a thruster is to know the sputtering rates of the eroding parts. The sputtered atoms were collected on an a circular strip of aluminum foil, and the sputtering yield was derived from RBS analysis of the collected film. The measurement of low energy sputtering yields will be continued at the Glenn Research Center (GRC) - NASA. It is proposed that the films will be generated at GRC and the RBS analysis performed at PNNL by Dr. Shuttha V. Shutthanandan. It is proposed that two to three films be delivered by Maris Manteneieks to PNNL beginning the middle of June, 2001 and subsequently two to three films in July and August for a total of approximately five films of molybdenum and possibly later five films of titanium.
Project Details
Project type
Exploratory Research
Start Date
2001-06-18
End Date
2002-03-31
Status
Closed
Released Data Link
Team
Principal Investigator