Measurement and analysis of K-shell lines of silicon ions in laser plasmas

Abstract

We present laboratory measurement and theoretical analysis of silicon K-shell lines in plasmas produced by Shenguang II laser facility, and discuss the application of line ratios to diagnose the electron density and temperature of laser plasmas. Two types of shots were carried out to interpret silicon plasma spectra under two conditions, and the spectra from 6.6Å to 6.85Å were measured. The radiative-collisional code based on the flexible atomic code (RCF) is used to identify the lines, and it also well simulates the experimental spectra. Satellite lines, which are populated by dielectron capture and large radiative decay rate, influence the spectrum profile significantly. Because of the blending of lines, the traditional G value and R value are not applicable in diagnosing electron temperature and density of plasma. We take the contribution of satellite lines into the calculation of line ratios of He-α lines, and discuss their relations with the electron temperature and density.

A laser wakefield acceleration facility using SG-II petawatt laser system

“…In this paper, we present the new petawatt-based laser wakefield acceleration facility. We also present in detail an online plasma density diagnostic employing the Nomarski interferometry [28][29][30][31][32][33][34] and show its importance toward the generation of LWFA electron beams.…”

“…To calculate the distribution of the plasma refractive index from the phase shift, Abel inversion transform shall be used. [28][29][30][31][32][33] When z is a constant, the formula is as follows:…”

Emission mechanism for the silicon He-α lines in a photoionization experiment

“…In the computations presented in this paper, we use radiativecollisional code based on FAC (RCF) [21,22] to calculate the spectrum emitted from a photoionizing plasma. RCF is collisional-radiative code that simulates plasma under nonlocal thermodynamic equilibrium conditions.…”

“…Thus, under some low resolution conditions, the influence of satellite lines needs to be taken into account in the calculation of line intensities. We denote by I R+ , I I+ and I F+ the intensities of the spectrum near three He-α lines, and the corresponding line ratios by R + and G + [22,25] . Specified to the Fujioka et al photoionization experiment, the forbidden line is invisible among the surrounding satellite lines, and it is impossible to get an exact I F .…”

Editorial review of HPLSE special issue on laboratory astrophysics

“…The papers published in this special issue can be broadly grouped within the following main applications to laboratory astrophysics: magnetized plasmas and collisionless shocks [1][2][3][4][5] , supersonic, radiative plasma flows and hydrodynamic instabilities [6][7][8][9][10] , experimental diagnostic development [11,12] , and direct astrophysical applications [13] . In addition, there were three review papers [14][15][16] that give an in-depth study of current applications in the field.…”