Neutron-Producing Gas Puff Z-Pinches on the Ceszar Linear Transformer Driver

Abstract

The gas puff Z-pinch is an intense source of neutrons when operated with deuterium [1] . Understanding the mechanisms of neutron production in gas puff Z-pinches is of key importance to gain insight on their fundamental physics and on their viability as a fusion concept. Here, we discuss the neutron production of single and double gas puff Z-pinches on the CESZAR Linear Transformer Driver (LTD) at ~0.5 MA currents [3] . LTDs are an attractive platform to conduct gas puff Z-pinch experiments, due to highly efficient energy conversion and high shot rates [2] . Comparing the implosion trajectory with models suggests that only ~60% of the machine current contributes to driving the implosion; the current coupling can be improved by pre-ionizing the gas before the main current pulse. Neutron yields of order 10 7 neutrons/pulse were recorded in double gas puffs with different outer shell gases. For a comparable mass and implosion time, using a higher atomic number gas in the outer shell results in more unstable plasma surface and smaller plasma radius at the location of instability bubbles, which can episodically increase the neutron yield. Pre-embedding an axial magnetic field can improve pinch stability, but at the cost of reduced compression.