Optimization of a modified plasma focus for ion beam generation

Abstract

This thesis presents a study of ion production process of a UNU/ICTP Plasma Focus which is a low energy device of 3 kJ. The optimization of the device for better ion beam production is also discussed. The study is based on both experimental and theoretical aspects, where suitable diagnostic techniques for the device characterization and ion beam characterization have been developed and employed, as well as, the simulation model based on both the kinematics and electronic aspects of the plasma generated by the device. Furthermore, the effects of the dynamics and the energy of the plasma current sheath on the ion beam generation are also investigated. The measurements of ion beam such as speed, kinetic energy and density are carried out using ion collector, PIN diode and Rogowski coil, when the device is operated at various pressures and charging voltages, as well as, variable physical configuration such as lengths and shapes of the anode. It has been demonstrated that more than 300 % increase in ion density and 80% of the ion energy from the original UNU/ICTP Plasma Focus configuration can be obtained. The ion beam energy is found to be related to the energy transferred into the plasma where the ion density is found to be related to the initially stored energy to the capacitor bank. Average Ar ion energy and Ar ion density of 1.47 MeV and approximately 4.49x10[superscript 19] ions/m[superscript 2], respectively, have been obtained from the plasma focus modified with a 19 cm taper anode and operating with 0.8 mbar Ar gas with the stored energy of 2.53 kJ.