Ion flux onto conducting and isolated surfaces in the beam-plasma discharge: Computer simulation
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MABEAM PROCESSES
Ion Flux onto Conducting and Isolated Surfaces in the BeamPlasma Discharge: Computer Simulation I. L. Klykova, E. G. Shustina, and V. P. Tarakanovb a
Kotel’nikov Institute of Radio Engineering and Electronics (Fryazino Branch), Russian Academy of Sciences, pl. Vvedenskogo 1, Fryazino, Moscow oblast, 141120 Russia b Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya ul. 13/19, Moscow, 127412 Russia Received June 26, 2009
Abstract—A physical model which allows the use of the program code KARAT for simulating the quasi steady state of the beamplasma discharge with plasma regeneration from a neutral gas is developed. The results of simulation of the modes of discharge at different potentials at the discharge collector are reported. The results obtained for isolated and grounded ion collectors are compared. DOI: 10.1134/S1063780X10130155
1. INTRODUCTION The authors of [1, 2] experimentally observed the effect of acceleration of ions escaping from the region of a beam–plasma discharge (BPD) at low magnetic field in the direction orthogonal to the discharge axis. The flux of ions obtained in such a manner and the dependence of its parameters on external parameters were experimentally studied. It was found that the ion energy could be varied within the range between 20 and 100 eV. Ion fluxes with such energies can be used for solving a number of technological problems related to etching of surfaces of materials in microelectronics and nanoelectronics. Etching with ions from the BPD exhibits a high degree of anisotropy and does not introduce any radiation defects. Of importance for technological applications are such characteristics of ion fluxes as the energy distribution function (EDF) of ions and their density. In [2], it was shown that the EDF of ions depends on such parameters, as the volt age at the collector, the accelerating voltage, and the external magnetic field strength. The topic problem is the search for a simple method of controlling the EDF of ions in order to obtain stable ion fluxes with speci fied energies and densities. In [3], the physical mechanism of the abovemen tioned phenomenon was clarified by computer simu lation. The simulation showed that broadband sto chastic oscillations developed in the BPD. In the region occupied by the electron beam, a strongly non equilibrium plasma is formed. Electrons of this region produce an additional current from the plasma to the end electrodes, and the increase in the electron cur rent yields an increase in the potential of the plasma in the region occupied by the beam. In turn, the potential gradient between this region and the periphery of the plasma defines the acceleration of the ion flux along
the normal to the axis of the system. The experiments supported the results of simulation. In [3], the initial stage of development of the insta bility on injection of a pulsed beam into the indepen dently produced plasma was studied. Such an approach restricted the time of analysis to 50–100 ns, since the p
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