Numerical Experiments on Radiative Cooling and Collapse in Plasma Focus Operated in Krypton

A model code for the radiative theta pinch

“…This radiation collapse occurs at a critical current of 1.6 MA (the Pease-Braginski current 15,16 ) for deuterium. For gases, such as Neon or Argon, because of intense line radiation, the critical current is reduced 17,18 to even below 100 kA, depending on the plasma temperature.…”

Plasma focus ion beam fluence and flux—For various gases

“…26 Speed-enhanced PF 21 was facilitated. Plasma focus neutron yield calculations, 10,32 current and neutron yield limitations, 9,11 deterioration of neutron scaling (neutron saturation), 33,34 radiative collapse, 3 current-stepped PF 35 and extraction of diagnostic data, [36][37][38] and anomalous resistance data 8,39 from current signals have been studied using the code. 2 As already pointed out in the introduction, the Model code has recently been used to produce reference numbers for deuteron beam number and energy fluence and flux and scaling trends for these with PF storage energy.…”

“…When the outwardly moving reflected shock meets the incoming piston the focus pinch phase begins, in which the pinch boundary moves slowly either inwards or outwards depending on the relative strengths of the magnetic pressure exerted by the piston and the increased hydrostatic pressure of the stagnated pinch. The radiation from the dense hot pinch plasma may become sufficient to affect the plasma dynamics in terms of radiative cooling and radiative collapse 3 in the case of high Z gases such as Ar, Kr or Xe or even Ne. From experimental observations, it has been suggested 4 that Ar (Z ¼ 18) is the transition gas in the sense that for gases with Z < 18 the pinching and any radiative collapse proceed as a column whereas for gases with Z > 18 radiative collapse breaks the column up into a line of collapsed dense hot spots.…”

Comparison of Measured Soft X-Ray Yield Versus Pressure for NX1 and NX2 Plasma Focus Devices Against Computed Values Using Lee Model Code

“…Information obtained includes axial and radial dynamics [13,31,32], SXR emission characteristics and yield [7,17,18,[33][34][35][36], design of machines [12, 13, 17, 18, 32-34, 36, 37], optimization of machines [13,17,18,31,33,38] together with the adaptation of the Filippov-type DENA [26]. Plasma focus SXR yield calculations [7,25,[34][35][36][37]40], pinch current and SXR yield limitations [6,39], optimization of SXR yield [7,[34][35][36][37], radiative collapse and cooling [41,42], current stepped PF [43], PF neutron yield calculations [44,45], current and neutron yield limitations [6,46], neutron saturation [47,48] and extraction of diagnostic data [49][50][51][52] and the anomalous resistance phase (RAN) data [53] from the current signals have been studied applyi...…”