Characterization of X-ray emission from laser generated plasma

Antonino Cannavò,Lucia Calcagno,Antonella Sciuto,Mariapompea Cutroneo,Massimo Mazzillo,Lorenzo Torrisi,Giovanni Ceccio,L Torrisi,M Cutroneo

doi:10.1051/epjconf/201816703004

Abstract

X-ray emission from laser generated plasma was studied at low (1010 W/cm2) and high (1018 W/cm2) intensity using ns and fs laser, respectively. Plasma characteristics were controlled trough the laser parameters, the irradiation conditions and the target properties. The X-ray spectra were acquired using fast detection technique based on SiC diodes with different active regions. The X-ray yield increases with the atomic number of the target, both at low and high intensity, and a similar empirical law has been obtained. The X-ray emission mechanisms from plasma are correlated to the plasma temperature and density and to the Coulomb charge particle acceleration, due to the charge separation effects produced in the non-equilibrium plasma. Functional dependences, theoretical approaches and interpretation of possible mechanism will be presented and discussed.

Highlights

When a high intensity laser pulse (I = 1010-1018 W/cm2) is focused on the surface of a target placed in vacuum the generated plasma acts as source of photons, from IR to Xrays regions, high energetic and thermal electrons and ions
The X-ray emission mechanisms from plasma are correlated to the plasma temperature and density and to the Coulomb charge particle acceleration, due to the charge separation effects produced in the non-equilibrium plasma
The results presented in this work have been acquired using three lasers operating in Italy, in Czech Republic and in France:

Summary

Introduction

When a high intensity laser pulse (I = 1010-1018 W/cm2) is focused on the surface of a target placed in vacuum the generated plasma acts as source of photons, from IR to Xrays regions, high energetic and thermal electrons and ions. The emission in a continuum spectrum is due to the interaction between electrons and the Coulomb potential of ions, the so called bremsstrahlung effect. Concerning the X-rays pulse duration, the overall emission is comparable with the laser pulse but changes according to the considered spectral range: the higher is the energy of the considered photons the shorter is the duration of the plasma emission. The peak of X-ray emissivity is located in the plasma region which combines both high temperature and high electron density, typically just beyond the critical surface density

Experimental set-up

Results

Target parameters

Laser parameters

Conclusion