Filippov type plasma focus as intense source of hard X-rays (E/sub x/≆50 keV)

Abstract

This paper evaluates the use of a plasma focus machine (Filippov type) as a pulsed intense source of hard X-rays. It is shown experimentally that discharging a capacitor bank of W=50 kJ in the new arrangement of the discharge parameters, one can deliver into the test cavity (volume of 6*10/sup 3/ cm/sup 3/) an average of /spl Phi//sub x/=8*10/sup -4/ J/cm/sup 2/. The delivered energy fluence varies in the range of 2*10/sup -4/ J/cm/sup 2//spl les//spl Phi//sub x//spl les/2.9*10/sup -3/ J/cm/sup 2/, depending on the probe position. The X-ray energy spectra were established by the differential absorption method using thermo-luminescent detectors (time-integrated spectra) or plastic scintillators (time-resolved spectra). The average energy of X-ray photons is 40 keV<E/sub x//sup av/<50 keV (20 keV/spl les/E/sub x//spl les/170 keV) and remains quasi-constant during the main part of the pulse (/spl sim/40 ns). The electron energy that can produce such bremsstrahlung radiation is in the range of 95 keV/spl les/E/sub e//spl les/170 keV. However, time-resolved experiments reveal that at each instant of time only one energy of electron beam occurs. The aforementioned radiation characteristics reveal new potentials for the plasma-focus machine for a variety of applications. Some insight into the physics behind production mechanism of quasi-monoenergetic relativistic-electron beams will be concurrently reviewed.