Effect of filling gas on hard x-rays and ion beam emission from a 2 kJ plasma focus device

ABSTRACT

The effects of the atomic number of the fill gas on hard x-ray and ion beam emission from a 2.2 kJ plasma focus were studied. Hydrogen, Nitrogen and Argon gases were used in the experiment. The anode voltage and discharge current were measured to calculate plasma inductance and to study the pinching regime in the three gases. The results showed that the heavier gas in the machine increases the duration of x-ray radiation, ion beam emission, and results in larger pinching plasma inductance. The Lee model suggests that the increase in the pinching plasma inductance can be explained by the occurrence of radiation collapse in the pinch operated with Argon gas. It is postulated that the occurrence of anomalous plasma heating may stop plasma compression and prevent the plasma from a complete collapse to reach near-zero radius.

KEYWORDS:

• Dense plasma focus
• radiation collapse
• anomalous heating

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was sponsored by the Sylvia Fedoruk Canadian Center for Nuclear Innovation and the Natural Sciences and Engineering Research Council (NSERC) of Canada.

Notes on contributors

R.A. Behbahani

R.A. Behbahani, Ph.D. Engineering Physics, University of Saskatchewan with experimental background on dense plasma focus (DPF), linear accelerators (LINAC), pulsed power, and RF technologies. He is currently working on RF linear accelerator systems for radiation cancer therapy.

S. Lee

S. Lee, Ph.D (1970 ANU) was Professor (now Emeritus) at University of Malaya (1984–1991) and Nanyang Technological University, National Institute of Education (NTU.NIE), Singapore (1991–2000). He held several awards including the Alexander von Humbold Research Fellowship (1975–76) and UNU Special Fellowship (86–87). He was on the editorial board of several journals and has been on the international organizing committee of many international conferences including the International Congress on Plasma Physics. He maintains an active interest in the modelling of the radiative plasma focus (continually developing the widely-used Lee Model on IPFS website). He was Founding President (now Advisor) of the Asian African Association for Plasma Training, now Founding Director of Institute for Plasma Focus Studies (www.plasmafocus.net). Besides supervising many PhD theses, he has trained/mentored many scientists including United Nations Univeristy, Third World Academy of Sciences and International Centre for Theoretical Physics Fellows in research workshops and training programes.

C. Xiao

C. Xiao, received his B.Sc. (1982) and M.Sc. (1984) degrees from the University of Science and Technology of China, Hefei, China and his Ph.D. (Dr.rer.nat., 1990) degree from the Ruhr-University Bochum, Germany. He is currently a professor in the Department of Physics and Engineering Physics, University of Saskatchewan, Canada. His current research interests include the physics, engineering, and application aspects related to plasma diagnostics and plasma devices such as tokamak, reversed field pinch, compact torus injector, and dense plasma focus. He is responsible for operation and research on the STOR-M tokamak and the University of Saskatchewan Compact Torus Injector.