Existing conventional megajoule plasma focus machines with 2-3 MA are producing fusion neutron yields of several times 1011 in deuterium operation,the fusion yields predominantly being the beam-gas target.Increasing the current to 10 MA and using 50％-50％D-T mixture will scale the neutron yield towards 1016 D-T fusion neutrons.In this work,we derive the Lawson criterion for plasma focus devices with a beam-target fusion neutron mechanism,so that we may glimpse what future technological advancements are needed for a break-even Q=1 plasma focus.We perform numerical experiments with a present-day feasible 0.9 MV,8.1 MJ,11 MA machine operating in 100 Torr in 50％-50％D-T mixture.The Lee Code simulation gives a detailed description of the plasma focus dynamics through each phase,and provides plasma and yield parameters which show that out of 1.1×1019 fast beam ions produced in the plasma focus pinch,only 1.24×1014 ions take part in beam-target fusion reactions within the pinch,producing the same number of D-T neutrons.The remnant beam ions,numbering at least 1019,exit the focus pinch at 1.9 MeV,which is far above the 115 keV ion energy necessary for an optimum beam-target cross-section.We propose to regain the lost fusion rates by using a high-pressure D-T-filled drift-tube to attenuate the energy of the remnant beam ions until they reach the energy for the optimum fusion cross-section.Such a fusion enhancement tube would further harvest beam-target fusion reactions by increasing the interaction path length(1 m)at increased interaction density(6 atm).A gain factor of 300 is conservatively estimated,with a final yield of 3.7×1016 D-T neutrons carrying kinetic energy of 83.6 kJ,demonstrating Q=0.01.

Institute for Plasma Focus Studies,32 Oakpark Drive,Chadstone VIC3148,Australia;Physics Department,University of Malaya,Kuala Lumpur 50603,Malaysia;INTI International University,Nilai 71800,Malaysia;Fuse Energy Technologies,Napiervillle QC JOJ 1LO,Canada

[1]Sing LEE-.Pushing the limits of existing plasma focus towards 1016 fusion neutrons with Q=0.01)[J].等离子体科学和技术（英文版）,2022(11):47-53

megajoule

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