The energy spectrum of neutral hydrogen atoms from a coaxial plasma gun

Abstract

To measure the energy spectrum of ions in a plasma, one must extract the ions without altering the spectrum. For a dense plasma this presents difficulties. A measure of the ion energy spectrum is given by the energy spectrum of neutral atoms produced by charge-exchange reactions. The neutral atom energy spectrum and the flux of neutral atoms have been measured for the hydrogen plasma from a coaxial gun. The measurements are made on the gun axis at 300 cm distance from the gun using as atom-ion converters both a gas cell and a metal surface. The two methods give for the converted ions spectra of the same shape with energy in the range 60-3000 eV. The maximum hydrogen atom flux is 1.4 × 1015 atoms cm-2 sec-1 eV-1 at 300 eV for the low-energy mode of gun operation and is 3.2 × 1014 atoms cm-2 sec-1 eV-1 at 800 eV for the high-energy mode.