Accession Number:

ADA440312

Title:

Plume Expansion and Ionization in a Micro Laser Plasma Thruster

Descriptive Note:

Research paper

Corporate Author:

ILLINOIS UNIV AT URBANA

Report Date:

2005-06-01

Pagination or Media Count:

14.0

Abstract:

Ion density measurements have been performed on the plasma generated by an ablative diode laser thruster using a negatively biased flat plate probe. The biased probe data was coupled with measurement of the ablation crater through use of a scanning electron microscope SEM. The SEM was used to analyze the post-pulse ablation spots to determine the volume of fuel ablated. The micro-laser plasma thruster micro-LPT discussed here ablates a target material through the back surface by focusing the laser through a transparent substrate in a process typically referred to as Transmissive mode T-mode ablation. The target materials investigated were polyvinyl chloride PVC and glycidyl azide polymer GAP, while the substrates used were cellulose acetate and KaptonTradename. Peak ion densities for a GAP targetacetate substrate were found to be 1.6x10exp 7cu cm, while for GAPkapton and PVCacetate the peak ion densities were 4.5x10exp 7cu cm and 7.9x10exp 9cu cm respectively. Although these corresponded to low ionization fractions calculated from the observed mass loss, the results indicate there are ways to improve the ionization fraction and in turn increase the specific impulse.

Subject Categories:

  • Lasers and Masers
  • Rocket Engines

Distribution Statement:

APPROVED FOR PUBLIC RELEASE