The X ray diagnostics of the argon filled dense plasma focus
An experimental investigation has been conducted to use a Dense Plasma Focus Machine as a prospected high intensity pulsed x ray source. The argon was chosen for the plasma discharge. An effort to reach the highest x ray intensity emission has been made. Although it has not yet been possible to operate with as high energy in argon as in hydrogen, the argon focus provides an intensified "point source" of x ray. Based on the diganostic data and the characteristic difference between argon and hydrogen, a theoretical model of the shock wave was proposed. The x ray energy spectrum of the focus was determined by a crystal spectrometer. Analyzing this spectrum, one can obtain a combined radiation from a 3 keV thermal plasma and a 48 keV electron beam bombarding the center electrode. The polarization of the x ray was measured at a direction perpendicular to the DPF axis. The change of the polarization with time indicated that the plasma impinged radially and then followed by an axial flow. The correlation of the x ray signal with the voltage signal showed that the plasma resistance was rising after the density reached its maximum, and associated the increase of the resistivity as a result of the ion-acoustic instability.