Spectral study of the electron beam emitted from a 3 kJ plasma focus

Abstract

In a 3 kJ Mather-type plasma focus device operated in neon, the electron beam emission is investigated using both a magnetic electron energy analyser (in the 30-660 keV range) and a Rogowski coil (coupled with an appropriate RC passive integrator). Several electron emission features are identified and correlated with the x-ray emission in different energy ranges. The electron beam output shows very strong correlation with the general plasma dynamics (breakdown, axial and radial acceleration, pinch and post-pinch phases). The electrons' energy spectra showed most of the electron emission concentrating below 200 keV and negligible emission with energy above 350 keV. At 4 mbar neon, the electron emission, as well as the beam energy, is the highest and has a good shot-to-shot reproducibility.

Study on electron beam emission from a low energy plasma focus device

“…The first spike may be resulted as the consequence of the break away electrons from the collapsing current sheaths due to the positive anode voltage. Similar types of observations were also reported earlier [25]. The second spike with FWHM around 60 ns appears just or near the moment of the maximum compression.…”

“…The multiple spikes in the electron beam signals were also reported in Ref. [25] and correlated with the different pinch stages of the plasma focus as well as the X-ray emissions of different photon energies. The first spike with lower amplitude appears just before the maximum compression followed by multiple spikes of higher intensities.…”

“…The most probable energetic electrons appears in the range from 80 to 110 keV. In a 3 kJ plasma focus, Patran et al [25] also observed that the energy of most of the emitted electrons lies below 200 keV and a few electrons have an energy above 350 keV. They noticed that the hard X-ray emission occurred mainly around 100 keV and found that the measured photon energy of hard X-ray is in agreement with the electron beam energy spectra.…”

“…The estimated time constant of Rogowski coil is nearly 0.8 ns. Since the electron beam emission lasts for a few tens of nanosecond [17,25] and, hence, the estimated rise time of Rogowski coil is best suited to pickup the time history of most of the periods of electron beam emission. The output of the Rogowski coil was fed to an oscilloscope through a suitable RC passive integrator to record the electron beam current.…”

Co-deposition of titanium and iron nitrides on SS-321 by using plasma focus

“…The dense plasma focus (DPF) is a simple device that produces high-density (∼10 25 -10 26 m −3 ) high-temperature (1-2 keV) plasma because of compression caused by the self-generated magnetic field [11,12], and it is found to be a bright source of different types of radiation including high-energy (25 keV to 8 MeV) high-fluence ions, relativistic electrons, X-rays and neutrons [13][14][15][16][17]. The energy spectrum of the ion beam emitted from the DPF is continuous following the spectral law dN i /dE ∼ E −k (where N i is the number of ions with kinetic energy E) from a few keV to several MeV with exponent k in the range 2-5.…”