Abstract:
This thesis describes the experimental investigations of the soft X-ray emission
and the plasma dynamics in a Mather type plasma focus device operated in different
gases (Neon, Helium, Deuterium, Neon+Helium) by changing different parameters
like charging voltage, capacitor bank energy, discharge current, anode shape, gas
pressure and influence of preionization. The objectives of the studies are to enhance
soft X-ray emission. The Rogowski coil, high voltage probe, PIN diodes and pinhole
camera masked with appropriate absorption filters are used for diagnostics.
Specifically attention is paid to tailor the radiation in different energy windows i.e. 1−
1.56 keV and 4−8.33 keV. A single 12.5 μF capacitor charged at 19-23 kV (2.25-3.3
kJ), with a field distortion type sparkgap as switch is used to transfer the energy to the
system.
In the first experiment, the effect of preionization caused by depleted uranium
(92U238) on soft X-ray and total X-ray emission is investigated by varying the neon
gas pressure with and without preionization. The X-ray yield and pinhole images are
found strongly influenced by the preionization and the pressure of the working gas.
The soft X-ray yield of 82.5 ± 4.0 J in 1.3–1.56 keV energy window is obtained with
preionization of neon gas at the optimum pressure, leading to the conversion
efficiency of 2.5% of the stored energy. The total X-ray yield with preionization is
195 ± 9.0 J in 4π geometry measured at the optimum pressure giving conversion
efficiency of 5.9%. The time integrated images indicate the broadening of X-ray
emission zone with preionization.
The second experiment is performed with helium as filling gas. The highest soft
X-ray yield of 0.25 ± 0.01 J is obtained without preionization, which increases to 0.50
± 0.02 J with preionization at optimum pressure. The total X-ray yield 1.50 ± 0.07 J
without preionization, is enhanced to 2.44 ± 0.11 J with preionization. The plasma
focus duration has been increased with preionization conforming enhancement and
improvement in X-ray. This has also been conformed by the symmetric and enlarges
pinch images with preionization.
