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

Journal Article · Thu Mar 15 04:00:00 EDT 2012 · Plasma Physics Reports

DOI:https://doi.org/10.1134/S1063780X12020080· OSTI ID:22047415

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 accelerated 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{sub c}) (where U is voltage between the grid and the vacuum chamber and U{sub 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 cylindrical 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.

• OSTI ID: 22047415
• Journal Information: Plasma Physics Reports, Journal Name: Plasma Physics Reports Journal Issue: 3 Vol. 38; ISSN PPHREM; ISSN 1063-780X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ARGON
ATOMIC BEAMS
CHARGE EXCHANGE
DOPPLER EFFECT
GLOW DISCHARGES
HELIUM
MOLECULAR BEAMS
NITROGEN
PLASMA
PLASMA POTENTIAL
PLASMA PRODUCTION