Beams of fast neutral atoms and molecules in low-pressure gas-discharge plasma

Abstract

Fast neutral atom and molecule beams have been studied, the beams being produced in a vacuum chamber at nitrogen, argon, or helium pressure of 0.1-10 Pa due to charge exchange collisions of ions accel erated in the sheath between the glow discharge plasma and a negative grid immersed therein. From a flat grid, two broad beams of molecules with continuous distribution of their energy from zero up to e(U + U c ) (where U is voltage between the grid and the vacuum chamber and U c is cathode fall of the discharge) are propagating in opposite directions. The beam propagating from the concave surface of a 0.2 m diameter grid is focused within a 10 mm diameter spot on the target surface. When a 0.2 m diameter 0.2 m high cylindri cal grid covered by end disks and composed of parallel 1.5 mm diameter knitting needles spaced by 4.5 mm is immersed in the plasma, the accelerated ions pass through the gaps between the needles, turn inside the grid into fast atoms or molecules, and escape from the grid through the gaps on its opposite side. The Doppler shift of spectral lines allows for measuring the fast atom energy, which corresponds to the potential difference between the plasma inside the chamber and the plasma produced as a result of charge exchange collisions inside the cylindrical grid.

Surface hardening by means of plasma immersion ion implantation and nitriding in glow discharge with electrostatic confinement of electrons

“…For processing of dielectric materials can be used broad beam sources of ions [4][5][6] or fast neutral molecules [7][8][9][10][11][12]. The sources allow nitriding of products without blunting their sharp edges.…”

“…The sources allow nitriding of products without blunting their sharp edges. Beams of fast neutral molecules can be also produced without sources through immersion of high-transparency grids in the discharge plasma filling the working chamber [7].…”

A high-current plasma emitter of electrons based on a glow discharge with a multirod electrostatic trap

“…In order to process a metal product with ions, it can be immersed in low pressure gas dis charge plasma and an ion accelerating negative voltage is then applied to the product [5]. However, dielectrics can be processed only using broad beam sources of ions [6] or fast molecules [7,8]. In order to process any materials with accelerated electrons, sources of broad electron beams are required [9].…”

A new method for synthesis of hard dielectric coatings

“…It was shown in [21] that beams of fast neutral atoms and molecules can be produced due to charge exchange Article published by EDP Sciences collisions of ions in the space charge sheaths near a negatively biased grid immersed in a low-pressure gasdischarge plasma. The plasma can be produced, for instance, by magnetron discharge.…”