Experiments on speed-enhanced neutron yield from a small plasma focus

Abstract

In order to operate a plasma focus at high axial sheath velocities, the geometry of the inner electrode (anode) of a 3 kJ Mather-type device was modified. Double-stage stepped-anode configurations were tested with the speed-enhanced region sufficiently long for a significant increase in speed but not long enough to allow the development of force-field flow-field separation at the end of the axial phase. Peak axial speeds up to 15 cm μs−1 were achieved. The neutron and soft X-ray productions were found to be sheath-velocity-dependent. A new scaling law for the non-beam component of the neutron yield is proposed.

Numerical Experiments Providing New Insights into Plasma Focus Fusion Devices

“…The code has been used extensively in several machines including UNU/ICTP PFF [2,7,8,10,11,[15][16][17], NX2 [9,12,18], and NX1 [18,19] and has been adapted for the Filippov-type plasma focus DENA [20]. A recent development is the inclusion of the neutron yield Y n using a beam-target mechanism [21][22][23][24][25], incorporated in recent versions [26,27] of the code (versions later than RADPFV5.13), resulting in realistic Y n scaling with I pinch [21,22].…”

“…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…”

Dynamics and Density Measurements in a Small Plasma Focus of Tens-of-Joules-Emitting Neutrons

“…For the beam-target fusion, two scaling laws have been proposed. In [8], it is assumed that the ion beam current is proportional to the pinch current and the relation Y b−t α I 0 is obtained while, in [9], from an inductive model for the beam acceleration, the relation Y b−t α I 4.5 0 is obtained. Using the results of several devices in a wide range of energies and currents (1 kJ to 1 MJ and 100 kA to 1 MA), the most accepted empirical scaling laws for the total neutron yield Y are Y ∼ 10 7 E 2 , with E in kilojoules, and Y α I…”

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.…”

“…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].…”