Energy Spectrum Of Neutral Atoms Research Articles

Atomic collisions in negative ion beam simulation

Several types of collision processes (such as stripping of negative ions and neutrals and ionization of gas molecules and atoms by negative ions) have been introduced in a simulation code of the extraction, acceleration, and transport of negative ions. The energy spectra of neutral atoms formed in the accelerator, for various values of the pressure in the transport region, have been computed. It will be shown that most of the neutrals are formed in the neighborhood of the thick extraction electrode. The effect of these neutrals on the charge-state distribution in the beam and the effect of the positive ion formation in the transport region on the ion trajectories will be discussed.

Determination of the energy spectra of neutral atoms formed by expansion of a laser-irradiated target

A time-of-flight determination was made of the energy spectra of the neutral component of a laser plasma to find the amount of nonionized material in the plasma flow. It was found that under these experimental conditions, the fraction of neutral atoms formed by recombination of ions during the flight was negligible ( 1 %). When the parameters of the laser pulse and a shell microsphere were matched in experiments using the Del'fin facility, this method could be used to monitor the state of the target material at the instant of maximum compression.

On the impact parameter dependence of detached electron energy spectra in H--He collisions

The impact parameter dependence of the energy spectra of neutral atoms produced in H--He collisions has been measured in the collision energy range from 126 to 500 eV using the time of flight (TOF) method. The TOF spectra reproduce the energy spectra of detached electrons, the impact parameter dependence of which are thus established. Excellent agreement with theoretical results in the zero-range potential approximation is obtained.

Energy distributions of alkali ions sputtered from alkali-halide crystals with energetic rare gas ion bombardment.

Relative energy spectra of sputtered alkali ions from three alkali-halide crystals (LiF, NaCl, and KCl) were measured by bombarding the energetic rare gas ions (He+ and Ar+) whose energies ranged from 10 keV up to 100 keV. It was found that the energy spectrum of K+ ions from a KCl crystal were in close agreement with the energy spectrum of sputtered ions from the metal surface in both respects of the shape and the peak position, whereas Na+ ions from an NaCl crystal were likely to fit to the energy spectrum of neutral atoms rather than that of ionic one, and Li+ ions sputtered from an LiF showed also neutral spectrum with slightly different asymptotic behaviors in the higher energy region.

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

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.