Secondary electron enhanced discharges in plasma source ion implantation
- MS-E526, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
The first published measurements of a plasma discharge enhanced by secondary electrons during plasma source ion implantation are presented. The ion implantation target consists of 1000 aluminum, automotive piston surrogates mounted on four racks; total surface area is over 16 m{sup 2}. The four racks are positioned parallel to each other, 0.25 m apart, in an 8 m{sup 3} vacuum chamber. The racks of pistons are immersed in a capacitive radio frequency plasma, with an argon gas pressure of 20{endash}65 mPa. Each plasma ion implanted into the target results in the emission of multiple secondary electrons. Langmuir probe measurements indicate that at high enough gas pressures, the energy of the secondary electrons can couple to the plasma, increasing the rate of ionization. Two different coupling mechanisms are observed. In the first, the secondary electrons directly ionize the background gas. In the second, the secondary electrons couple to the thermal electrons through a beam-plasma instability. Measurements of the instabilities are in agreement with two-dimensional particle-in-cell simulations.
- OSTI ID:
- 664661
- Journal Information:
- Journal of Applied Physics, Vol. 84, Issue 11; Other Information: PBD: Dec 1998
- Country of Publication:
- United States
- Language:
- English
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