Production of atom flows at materials evaporation by laser radiation
Abstract
Parameters of atom fluxes obtained by laser evaporation from the surface of a massive target are studied. The target consists of Al and Ag. Total quantity of substance removed from the surface of the target at the expense of laser radiation is measured by weighing. Energy distribution and quantity of evaporated atoms are determined by resonance radiation absorption. Duration of evaporation is identified by measured time characteristics of thermal radiation of the target surface. The head part of the flux comprising plasma is investigated by double probe and RF-signal absorption (lambda = 3 cm). Optimum energy density of an evaporating pulse is shown to equal 3-4 J/sq cm when using monopulse ruby laser of 3.5 J beam energy and duration of 30 ns. Quantity of evaporated substance in the flux at this energy density makes up 4x10 to the 16th and 2x10 to the 17th power at. per pulse for Al and Ag respectively. At optimum energy density drops and plasma make up not more than 20% of the vapor mass. Here the energy of vapor atoms in the flux is equal to 2 eV and the head part of the flux moves at the velocity corresponding to an energy of 130 eV. These requirements comply with requirements to the flux for simulation of natural inflow of impurities into plasma at the expense of sputtering and arc-formation.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- 1986
- Bibcode:
- 1986STIN...8812074V
- Keywords:
-
- Atoms;
- Evaporation;
- Laser Outputs;
- Plasma Diagnostics;
- Distribution Functions;
- Silver;
- Time Dependence;
- Lasers and Masers