Electron Density In Laser-produced Plasma Research Articles

Intensity clamping in the filament of femtosecond laser radiation

We have studied numerically the evolution of the light field intensity and induced refractive index of a medium upon filamentation of femtosecond laser radiation in air. It is shown that the intensity clamping results from the dynamic balance of optical powers of nonlinear lenses, induced by radiation due to the Kerr nonlinearity of air, and laser plasma produced during photoionisation. We have found the relation between the peak values of the light field intensity and the electron density in laser-produced plasma, as well as the transverse sizes of the filament and the plasma channel.

极化X光谱诊断铝激光等离子体的电子密度

In order to accurately diagnose the electron density of laser-produced plasma,the method of relative intensity ratio of helium-like resonance to combination lines was proposed based on the polarization spectrum.It took into account polarization characteristics of the X-ray in laser-produced plasma,modified the real intensity ratios of the resonance to intercombination lines of He-like ions,then derivated the density of plasma.The experiment was carried out at the 2×10 J laser facility at Laser Fusion Research Center of,China Academy of Engineering Physics(CAEP).X-ray spectra emitted from the aluminum plasmas were recorded by polarized PET(002) crystal spectrometer.By correcting two Al helium-like spectra,it was calculated that the electron density was about 1.5×1 020 cm-3.The experimental results showed that the arithmetic was adapted to diagnose laser-produced high temperature high-density plasmas.

DIAGNOSTICS OF ELECTRON DENSITY OF LASER-PRODU-CED PLASMA FROM THE XUV SPECTRA OF AgXIX

The XUV spectra from AgXIX of laser-produced plasma are measured. The density dependence of △n= 0 (4-4) transitions from AgXIX has been studied in a density range 1017-1022 cm-3 with the collisional radiative model. The theoretical model included the effect of cascading from n= 5 states on the population of the n =4 levels. In addition, optical depth effects on the line intensities were considered. The two transitions of 4d2D5/2 4f2F7/2 and 4p2P3/2-4d2D5/2 remain close to each other and are unblended with other lines. Calculations of their radiation intensity ratio vs the electron density are performed. Electron density of laserproduced plasma has been deduced from the ratio.