Study of electron beams emitted from plasma focus operated with various gases

The Lee model is extended to study and characterize the electron beams emitted from plasma focus devices operated with different gases. It is then applied to characterize the electron beams emitted from low and high energy plasma focus devices operated with deuterium gas (PF 400 J, ICTP PF, PF 2.2 kJ, PF 2.7 kJ, NX2, INTI PF, PF 10 kJ, NX3, PF 115 kJ, PF 1000). The numerical experiments on the NX2 plasma focus device at 15 Torr of deuterium give the following results: Electron fluence = 5.7x10²² m^-2, electron flux = 16x10²⁹ m^-2 s^-1, the relativistic kinetic mean energy of the electron = 56 keV, electron number = 2x10¹⁶, electron current = 91 kA, and damage factor = 2.7x10¹² Wm^-2s⁰.5. Then, the effect of pressure on the beam characteristics is studied. The energy of the beam at pinch exit changes from around 57 J (1.9% of the stored energy E0) to 176 J (6%E0) with maximum value of 180 J (6.1%E0) at 15 Torr and these results are compared with the measured values 3.2%E0 on NX2. Scaling trends are suggested for electron beam characteristics. The energy fluence and the power flow density (energy flux) have a variation 4.3 -265x10⁷ J m^-2 and 2.2 - 19x10¹⁵ W m^-2, respectively. The electron beam current ranges from 12 to 700 kA being 9% -35% of Ipeak. The energy beam Y_EB scales on average as Y_EB = 6.55 x E₀^1.45 at energies in the 1 to 500 kJ regions (Y_EB in J and E0 in kJ), and Y_EB = 2 x 10^-6 I_peak^-3.14, Y_EB = 1 x 10^-6 I_pinch^-3.53(Ipeak and Ipinch in kA and Y_EB in J). The electron beams features emitted from the plasma focus device (AECS PF1, AECS PF2 and INTI PF) operated with various gases (nitrogen, neon and argon) are also studied and discussed. These results provide much needed benchmark reference values and scaling trends for electron beams of a plasma focus (author).