Laser and Particle Beams

Research Article

Double layer (DL) formation in laser-produced plasma

Shalom Eliezera1 and Ariold Ludmirskya1

a1 Soreq Nuclear Research Center, Yavne 70600, Israel


It is shown that appropriate conditions for DL formation may be created in laser produced plasma. In particular, a ‘feedback’ mechanism is suggested:

Wave instabilitiesabsorption of laser energyinward heat fluxDL formationheat flux inhibitionwave instabilities

Plasma-target potentials and plasma-currents, produced by Nd. laser intensities (IL) between 1012 to 1015 W/cm2, were measured in situ. These measurements seem to be the first direct evidence of DLs in laser produced plasma. Electric fields of EDL xs223C 5 × 105 to 5 × 106 Volts/cm and widths of 10 to 100 Debye lengths are estimated for the DL.

Scaling laws are derived for the measured extremum potentials (V) and currents (I): S0263034600000331_inline1. Two different slopes were obtained experimentally, one slope equal to α = β = 1·0 for IL < 1014 W/cm2 and another of α = β = 0·4 for IL > 1014 W/cm2. These data are explained for temperature scaling law S0263034600000331_inline2 for the low irradiance and S0263034600000331_inline3 for the high irradiance. While the first scaling law is consistent with inverse bremsstrahlung absorption, the second scaling necessitates other absorption processes. Potential and current probes are suggested as useful devices in detecting wave plasma instabilities.

(Received May 10 1983)