Electron Beam Properties Emitted From Deuterium Plasma Focus: Scaling Laws

The Lee model is extended to study and characterize the electron beams emitted from plasma-focus devices. It is then first applied to characterize the electron beams emitted from low and high-energy plasma focus operated with deuterium gas. The numerical experiments on NX2 device at 15 torr of deuterium give the following results: electron fluence = 5.7 × 10
²²
m
^-2
, electron flux = 16 × 10
²⁹
m
^-2
s
^-1
, the relativistic kinetic mean energy of the electron = 56 keV, electron number = 2 × 10
¹⁶
, electron current = 91 kA, and damage factor = 2.7 × 10
¹²
W · m
^-2
s
^0.5
. 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 E
₀
) to 176 J (6%E
₀
) with maximum value of 180 J (6.1%E
₀
) at 15 torr, and these results are compared with the measured values 3.2%E
₀
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 - 265 × 10
⁷
J · m
^-2
and 2.2 - 19 × 10
¹⁵
W · m
^-2
, respectively. The electron beam current ranges from 12 to 700 kA being 9%-35% of Ipeak. The energy beam YEB scales on average as YEB = 6.55 × E
₀
^1.45
at energies in the 1 to 500 kJ regions (Y
_EB
in J and E
₀
in kJ), and Y
_EB
= 1 × 10
^-6
I
_pinch
^3.53
and Y
_EB
= 2 × 10
^-6
I
_peak
^3.14
(I
_peak
and I
_pinch
in kA and Y
_EB
in J). These results provide much needed benchmark reference values and scaling trends for electron beams of a plasma focus operated in deuterium gas.