Kp. Shamrai et al., DISCHARGE DISRUPTIONS IN A HELICON PLASMA SOURCE, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 15(6), 1997, pp. 2864-2874
Citations number
22
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
We study experimentally and theoretically stable regimes and discharge
disruptions in a helicon plasma source. At fixed input power and gas
pressure, stable operation of the source is possible below some critic
al value of magnetic field B-cr. The plasma density increases with the
magnetic field and reaches a maximum value n(max) at B-cr; after whic
h the discharge disruption occurs. Both B-cr and n(max) increase almos
t linearly with the input power and the rate of increase is increasing
with the pressure. Matching of the plasma load to the rf power source
improves when approaching the disruption point, and becomes perfect a
t the critical field. The theory of discharge disruptions assumes the
power absorption in a helicon source to arise from the linear conversi
on of helicon waves into electrostatic waves at the plasma edge. The c
alculated dependence of the absorbed power on the plasma density turns
out to be nonmonotonic with minima at antiresonances of the electrost
atic wave excitation. This explains qualitatively principal peculiarit
ies of discharge disruptions. The calculated plasma impedance is in ag
reement with experimental value within a factor of 2. (C) 1997 America
n Vacuum Society. [S0734-2101(97)00706-9].