Generation of a long, plasma-based waveguid by capillary Z-pinch for acceleration of electrons: Theory and experiment

Abstract

Summary form only given. The study presents results of theoretical and experimental studies of the plasma-based waveguides produced by the capillary Z-pinches in long (~0.5 m), gas-filled capillaries. The plasma waveguides are developed for the future acceleration of electrons by the Hungarian Extreme Laser Infrastructure (ELI). The waveguide properties of the plasma columns generated in hydrogen, argon and xenon gases are compared with each other. For experimental verification of the theoretical results, an experimental set-up has been developed at University of Pecs to generate the plasma-based waveguides. The waveguides are created by using the so-called C-C excitation scheme. The plasma is produced in an Al2O3-ceramic capillary by discharge of a peaking capacitor Cp = 6 nF, which is resonantly charged by a six-stage Marx-generator (Umax ~ 200 kV, Imax ~ 20 kA, C = 6 nF, L = 8 mH). The refraction index of the waveguide was investigated by measuring the intensity distribution of a probe beam passed through the plasma column. The probe beams are generated by the XeCl (308 nm) laser, N2 (337 nm) - dye (400-800 nm) laser system or Nd:YAG laser system (1064, 532 or 355 nm) synchronised to different moments of the Z-pinch. The parameters of the discharge configuration have been optimized by using the two-fluid, two-temperature, two-dimensional MHD model of the capillary Z-pinch plasma. The computer simulations and experiments showed that the waveguide parameters can be adjusted in the experimental set-up to match requirements of the laser acceleration of electrons. This study was supported by the Hungarian Extreme Light Infrastructure (ELI) project (hELIos, ELI 09-1-2010-0013, ELIPSZTE).