Emission of High-Energy Ions in the SHOTGUN III Divergent Gas-Puff Z-Pinch Experiment

Takasugi, Keiichi; Iwata, Masayuki; Nishio, Mineyuki

doi:10.1088/1742-6596/688/1/012120

Cited by 3 publications

(2 citation statements)

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“…As shown in figure 3(d), a very characteristic feature of the pinhole images is the detection of concentric circles. These circles were also observed in DPFs [21,22] and Ar gas-puff z-pinches [23]. However, the data from those experiments were not sufficient to answer a key question: does the annulus represent a real spatial distribution of an ion source or is it created by magnetic fields after ion acceleration?…”

Section: Angular Spatial and Spectral Properties Of Ion Emissionmentioning

confidence: 98%

Ion acceleration mechanism in mega-ampere gas-puff z-pinches

et al. 2018

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Acceleration of high energy ions was observed in z-pinches and dense plasma foci as early as the 1950s. Even though many theories have been suggested, the ion acceleration mechanism remains a source of controversy. Recently, the experiments on the GIT-12 generator demonstrated acceleration of ions up to 30 MeV from a deuterium gas-puff z-pinch. High deuteron energies enable us to obtain unique information about spatial, spectral and temporal properties of accelerated ions. In particular, the offaxis ion emission from concentric circles of a ∼1 cm diameter and the radial lines in an ion beam profile are germane for the discussion of acceleration mechanisms. The acceleration of 30 MeV deuterons can be explained by the fast increase of an impedance with a sub-nanosecond e-folding time. The high (>10 Ω) impedance is attributed to a space-charge limited flow after the effective ejection of plasmas from m=0 constrictions. Detailed knowledge of the ion acceleration mechanism is used with a neutron-producing catcher to increase neutron yields above 10 13 at a currentof2.7 MA.

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Section: Angular Spatial and Spectral Properties Of Ion Emissionmentioning

confidence: 98%

Ion acceleration mechanism in mega-ampere gas-puff z-pinches

et al. 2018

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“…We suppose that a better understanding of the intriguing ion pinhole images and the correct answer to the question of where ions are accelerated could help with identification of the acceleration mechanism. Interestingly, characteristic annuli were observed by ion pinhole cameras both in dense-plasma foci [18][19][20][21][22][23][24][25] and in gas-puff z-pinches [26][27][28]. This is an important result, since it indicates that the acceleration of high-energy ions can take place in an analogous way in both devices.…”

Section: Introductionmentioning

confidence: 85%

Spatial distribution of ion emission in gas-puff z-pinches and dense plasma foci

Klír

Shishlov

Jackson

et al. 2020

Plasma Phys. Control. Fusion

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Mega-ampere dense plasma foci and deuterium gas-puff z-pinches can accelerate deuterons to multi-MeV energies. Diagnostic measurements of the properties of these ions provide information about ion acceleration in z-pinch plasmas. In particular, the results from ion pinhole cameras seem to be useful for the discussion of ion acceleration mechanisms. Recently, we have used various configurations of ion pinhole cameras in deuterium gas-puff experiments on the GIT-12 generator at the Institute of High Current Electronics in Tomsk and on the HAWK generator at the US Naval Research Laboratory in Washington. The stack of radiochromic films and CR-39 solid-state nuclear track detectors recorded deuterons with energies up to 30 MeV. From our ion diagnostics, we obtained the spatial distribution of the ion source and the ion-beam divergence during the ion emission. This ionbeam divergence was found to decrease with increasing deuteron energy. At 20 MeV, the divergence of each of the individual micro-beams that composed the ion source was on the order of 10 mrad. The deflection of each micro-beam due to the azimuthal magnetic and/or radial electric fields resulted in radial stripes observed by the beam-profile detectors. By analyzing the ion pinhole images, we found that the deuterons were emitted both from a central spot and from a ring-shaped region with a rather large diameter, on the order of 1 cm. The origin and particular diameter of this ring is attributed to the geometry of the electrodes and to the distribution of the current density before the disruption.

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