XXXIV International Conference on Plasma Physics and CF, February 12 – 16, 2007, Zvenigorod

Metal-hydride cathode influence on compensation of hydrogen ion beam extracted from PIG ion source

I.A. Afanas’eva, A.A. Bizyukov, Ye.V. Klochko, I.N. Sereda

KNU by V.N. Karazin, Kharkov, Ukraine, e-mail:

A number of advantages at solids treatment give a plasma ion sources applying. However ion beam transportation in the free-field space together with the problem of charge accumulation on a treatment surface conjugates with the difficulties over the influence of beam own spatial charge [1]. In view of it the problem of charge neutralization of ion beams is given a special consideration. One of the methods of solving such a task is transmission of positive ion beam through ballast gas, or applying a system of interpenetrative electron and ion beams which move in the same direction that preferable in the conditions of high vacuum [2]. However it assumes the presence of additional units, for instance, cathode-compensator etc., which sufficiently perturb source plasma and increase power inputs. Discovered in the papers [3,4] compensation of ion beam extracted through the hole in the centre of disk cathodes from PIG discharge at certain discharge parameters (Р10-5 mm.Hg.andН500Oe) [4] allows to avoid the problem of creating additional compensation units.

At hydrogen using as working gas of ion source it is promising to apply metal-hydrides of Zr-V system as discharge cathodes. The main advantages of such compounds are high density hydrogen packing in metallic matrix, the possibility of its long term storage and realizing the hydrogen supply in wide pressure range. Furthermore in this case the opportunity of power inputs decreasing on excitation, dissociation and ionization of molecules and atoms of hydrogen at the expense of it’s metal-hydride activation is possessed [5].

In this work the physical processes which are responsible for positive hydrogen ion beam compensation extracted in axial direction from reflective discharge with metal-hydride (Zr50V50Hx) cathode are investigated. It has been shown, that phenomena of hydrogen ion beam compensation shifts in the range of higher pressures (Р510-5…510-4mm.Hg), observes only from the side of metal-hydride (the second cathode was manufactured from copper) and depends on initial hydrogen saturation degree of metal-hydride element. At discharge rearrangement following by dropping and then changing sign of positive component of current on Faraday cup the drastical increasing of HF oscillation frequency is observed. The appearing of LF oscillation in the range of 50…60kHz is observed as well.

References

[1].Timothy A. Grotjohn. Rev.Sci. Instrum. 1994, 65(4), 1298.

[2].М.Д. Габович. УФЖ, 1979, 24, 257.

[3].Ю.Е. Крендель, А.С. Ионов. ЖТФ, 1964, 34(7), 1199.

[4].Г.В. Смирницкая, Р.П. Баберцян. Радиотехника и электроника. 1966, 10, 1897.

[5].Yu. F. Shmal’ko, Ye. V. Klochko, N. V. Lototsky. Int. J. Hydrogen energy. 1996, 21, 1057.

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