Target laser plasma scale effect in electron temperature measurements by electric potential probe technique

We have investigated the e.m.f. of the double charge boundary layer of the laser metal target plasma under the Nd-laser pulses with duration ∼10 ns, wavelengths 1.06, 0.53 and 0.265 intensities from 109 to 1013 W/cm2 and laser beam focal spot sizes d ∼(0,08 divided-by 3) mm. The measurements of the e.m.f. were carried out by electric potential probe technique. It was shown for the first time that the probe signal corresponds to the double charge layer potential at the plasma boundary only if plasma size /∼d is small in comparison with the distance L ∼ 5 mm of the probe from the target, (d/L)=η <1