An improved radiative plasma focus model calibrated for neon-filled NX2 using a tapered anode

Abstract

This paper presents a 4-phase radiative plasma focus model, where the dynamics of the current sheath is represented using Lee's model. The model is based on the snowplow model in the axial phase and the slug model in the radial phase, complemented with sensible estimations made for the plasma parameters. The x-ray emission characteristics are investigated using a corona plasma equilibrium model. A refinement to the code was made, firstly by taking into account the tapering of the anode in the axial phase and secondly by including the energy loss due to recombination radiation in the slow compression (radiative) phase. Our improved code was calibrated for the NX2, a 3 kJ plasma focus device, operated in neon at a pressure range of 4-7 mbar with a tapered copper anode. An additional macro was programmed to the code in order to automate the curve fitting of the simulated current traces with those obtained experimentally. The resulting theoretical x-ray yield predictions are compared against experimental data, showing good agreement in terms of pressure dependence trends. The model, however, appears to consistently underestimate the absolute x-ray yield when compared with the experimentally obtained values.

Numerical Experiments Providing New Insights into Plasma Focus Fusion Devices

“…The vital role of a finite small disturbance speed discussed by Potter in a Z-pinch situation [6] was incorporated together with real gas thermodynamics and radiation-yield terms. This version of the code assisted other research projects [7][8][9][10][11][12] and was web published in 2000 [13] and 2005 [14]. Plasma…”

Correlation of measured neon soft X-ray pulses of the INTI plasma focus with the reflected shock phase at 12KV

“…The code has been used extensively in several machines including UNU/ICTP PFF, [3][4][5][6][7] NX1, 8 NX2, 5,[8][9] and has been adopted for the Filippov-type DENA. 10 A recent development is a template that shows the correlation of the neon SXR signal with the plasma focus dynamics 2 and the inclusion of the anomalous resistance phase to simulate the Type 2 high inductance plasma focus machine.…”

Optimizing UNU/ICTP PFF Plasma Focus for Neon Soft X-ray Operation

“…A factor of two in shock speeds gives a factor of four in temperatures, leading to a difference in fusion cross sections of approximately 1000 at the range of temperatures that we are dealing with. This version of the code assisted other research projects [5]- [7], [14]- [16] and was web published in 2000 [17] and 2005 [18]. Plasma self-absorption was included in 2007 [16], improving the SXR yield simulation.…”

“…This version of the code assisted other research projects [5]- [7], [14]- [16] and was web published in 2000 [17] and 2005 [18]. Plasma self-absorption was included in 2007 [16], improving the SXR yield simulation. The code has been used extensively in several machines including UNU/ICTP PFF [2]- [6], [14], [15], [19], NX2 [7], [16], [20], and NX1 [20], [21] and has been adapted for the Filippov-type plasma focus DENA [22].…”

“…Plasma self-absorption was included in 2007 [16], improving the SXR yield simulation. The code has been used extensively in several machines including UNU/ICTP PFF [2]- [6], [14], [15], [19], NX2 [7], [16], [20], and NX1 [20], [21] and has been adapted for the Filippov-type plasma focus DENA [22]. A recent development is the inclusion of the neutron yield Y n using a beam-target mechanism [23]- [27], incorporated in recent versions [8] of the code (versions later than RADPFV5.13), resulting in realistic Y n scaling with I pinch [23], [24].…”