The Studying Of Hard X-ray Energy Spectrum On Ultra Short Pulse Laser Interaction With Solid Target

With the development of ultra-short pulse laser, Tabak brought forward the idea of"fast ignition". According to his assumption, it's possible to ignite the nuclear fuel with the hot electrons produced by the interaction between the laser and plasma. So, in the community of strong field physics, the characteristic of hot electrons such as temperature, quantity and direction of emission is always the focus of people's interest. The hard X-ray produced by the interaction between hot electrons and solid targets is often used to deduce the information about hot electrons.This paper describes the experimental facilities and measuring methods of X-ray detection. The count per shot due to background noise was reduced to 10^-4 /shot by applying the techniques of shielding and linear gate. The intensity of the P polarized light is about I≈5.5×10¹⁶ W/cm²,λ= 746nm.The experimental result shows that the energy of X ray is almost less than 100kev and the temperature of hot electrons are 7.4±0.7KeV and 19.5±1.6 KeV respectively, under the condition that the angle of incidence of laser is about 45 and the solid angle of detection is about 4.5×10^-6. The probability of single photon is about 95%. Based on theoretical analysis, resonance absorption is probably the dominant process for hot electron generation which can explain the higher energy part of the spectrum. On the other hand, the lower part of the spectrum is possibly caused by those electrons which quiver with the vibration of the electric field produced by the laser.