Optimization of dense plasma focus for higher neutron yield

Abstract

Summary form only given. The optimization of a dense plasma focus for higher neutron or X-rays yield is dependent on a number of factors such as the geometry and structure of inner and outer electrodes, length and material of an insulator sleeve, type and pressure of a filling gas, rate of discharge current, and the electrode polarity. These parameters are interrelated in a complicated way in order to get good pinching current or peak tube current Ip. Plasma focus fusion yields on a wide range of plasma focus devices have been reported to scale simply with Ip, such as Ip. This is consistent with a plasma with the same parameters (density, and temperature) scaling with size of plasma which in theory should give a scaling law of Ip. The possibility of a scaling law with Ip <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sup> , for the value of n greater than 4, is explained in terms of the drive parameter and energy considerations. The required plasma energy for the higher neutron yield is estimated for few joules to mega-joules plasma focus devices. The results show that the yield saturation effect is significant for mega-ampere devices with mega-joule energies. For small plasma foci, applications drive the need for high neutron yield rate instead of yield per shot. We discuss the limitations of small high repetition rate plasma focus devices and propose new experiments to confirm and break the neutron yield limits of both high and low energy plasma focus devices. These experiments would also be helpful to find the best scaling parameters for the X-rays in a low energy plasma focus device.