Hydrogen plasma dynamics in the spherical theta pinch plasma target for heavy ion stripping

Loisch, Gregor; Xu, Genhui; Blažević, A.; Cihodariu-Ionita, B.; Jacoby, J.

doi:10.1063/1.4919851

Cited by 4 publications

(5 citation statements)

References 11 publications

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“…Frame (b) indicates a kind of disrupted shape caused by the plasma being axially ejected and partially colliding with the vessel due to the lack of a sufficient confinement on both sides to withstand the compression. This ejection is more clearly demonstrated in an earlier experiment [13]. The free electron density has already strongly decreased at this point, but the free electron line density is still on a rising slope.…”

Section: Resultssupporting

confidence: 55%

“…Consequently, spectroscopy and interferometry do not monitor equal regions in this specific configuration. Nevertheless, in an experiment, in which a collimating lens in front of the fiber as well as diaphragms were used, a similar time behavior of the spectroscopic results occurred showing comparable narrow density peaks [13].…”

Section: Resultsmentioning

confidence: 73%

“…Nevertheless, the results for a pressure of 20 Pa are clearly showing a region of saturation at high voltages. This saturation can be explained by the load voltage having already passed an optimal pressure/voltage ratio [7,13]. Unfortunately, this characteristic can not be investigated further at the higher end of the pressure range, because the electrical system regarding the load voltage is limited to 20 kV.…”

Section: Resultsmentioning

confidence: 99%

“…Spectroscopic methods like line broadening and line intensity ratios, however, which have always been our diagnostic approach, can only provide the number of free electrons per volume. From such a measurement, a line density is not easily derived since a theta-pinch plasma is inhomogeneous and changes its geometric dimensions rapidly [13]. Furthermore, for an actual neutral particle density and ionization degree measurement, respectively, a supporting electron temperature estimation is necessary [14].…”

Section: Introductionmentioning

confidence: 99%

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Measurement of the free electron line density in a spherical theta-pinch plasma target by single wavelength interferometry

Christ

Cistakov

Iberler

et al. 2021

J. Phys. D: Appl. Phys.

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A single wavelength heterodyne interferometer has been set up to investigate the free electron density integrated axially along the line of sight (line density) in a theta-pinch plasma to determine its applicability as a plasma target for ion beam stripping. The maximal line density reached in this experiment was 3 . 57 ± 0 . 28 × 10 18 cm−2 at 80 Pa and 20 kV. The findings demonstrate the pulsed character of the line density and its increase by raising the load voltage and the working gas pressure. Additionally, the results were compared with spectroscopic free electron density estimations, which were carried out by H β -line broadening and peak separation. The time behavior of the line density indicates that its peak value is delayed by about 10 µs compared to the spectroscopic results. This effect is due to the formation of an extended, magnetically compressed plasma column in the vicinity of the current maximum, although the highest volumetric free electron density is reached near the current zero crossing. Since the line density is an essential parameter in describing the stripping capabilities of the plasma target, the interferometric diagnostic is superior to a spectroscopic diagnostic, because it directly provides integrated values along the line of sight. Furthermore, the measurements of the line density in this experiment partially show nonphysical negative values, which is due to gaseous effects and residual shot vibrations.

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Section: Resultssupporting

confidence: 55%

Section: Resultsmentioning

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Measurement of the free electron line density in a spherical theta-pinch plasma target by single wavelength interferometry

Christ

Cistakov

Iberler

et al. 2021

J. Phys. D: Appl. Phys.

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“…In the experiments described here, a spherical theta pinch has been used as a plasma device, as described in Refs. [16][17][18][19][20][21][22][23][24]. The energy stored in a capacitor bank is transferred to the target by a coil surrounding a 4 l glass vessel filled with the working gas.…”

mentioning

confidence: 99%

Determination of Hydrogen Density by Swift Heavy Ions

Barriga-Carrasco

Blažević

et al. 2017

Phys. Rev. Lett.

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A novel method to determine the total hydrogen density and, accordingly, a precise plasma temperature in a lowly ionized hydrogen plasma is described. The key to the method is to analyze the energy loss of swift heavy ions interacting with the respective bound and free electrons of the plasma. A slowly developing and lowly ionized hydrogen theta-pinch plasma is prepared. A Boltzmann plot of the hydrogen Balmer series and the Stark broadening of the H_{β} line preliminarily defines the plasma with a free electron density of (1.9±0.1)×10^{16} cm^{-3} and a free electron temperature of 0.8-1.3 eV. The temperature uncertainty results in a wide hydrogen density, ranging from 2.3×10^{16} to 7.8×10^{18} cm^{-3}. A 108 MHz pulsed beam of ^{48}Ca^{10+} with a velocity of 3.652 MeV/u is used as a probe to measure the total energy loss of the beam ions. Subtracting the calculated energy loss due to free electrons, the energy loss due to bound electrons is obtained, which linearly depends on the bound electron density. The total hydrogen density is thus determined as (1.9±0.7)×10^{17} cm^{-3}, and the free electron temperature can be precisely derived as 1.01±0.04 eV. This method should prove useful in many studies, e.g., inertial confinement fusion or warm dense matter.

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Compression of an accelerated plasma cloud in a cone

et al. 2019

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This paper describes first results of a novel compression method for a plasma by acceleration into a glass cone. The plasma is generated by a pulsed-power-driven coaxial plasma accelerator, prefilled with 2% hydrogen in a helium mixture. The pulse forming network of the experiment has a total capacitance of 27 μF at a maximum voltage of 10 kV. The low inductance of 130 nH leads to an average frequency of about 86 kHz and high current rise rates in the 1011 As range. Due to the high current of up to 150 kA, the Lorentz force accelerates the plasma depending on pressure and applied voltage to velocities in the 104 ms order. After ejection, the plasma moves into several cone geometries, placed at the end of the electrodes. The conducted studies focus on the Stark-broadening of spectral lines to determine the electron density changes due to the compression. Because of the wide broadening at high electron densities, the well-known Hβ line broadening method is not eligible for cone compressed plasmas. Alternatively, the broadening of the Hα line and a copper line has been used. The achieved electron densities could be increased approximately two orders of magnitude from 1015 cm−3 without the cone to 1017–1018 cm−3 with cone compression.

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Hydrogen plasma dynamics in the spherical theta pinch plasma target for heavy ion stripping

Cited by 4 publications

References 11 publications

Measurement of the free electron line density in a spherical theta-pinch plasma target by single wavelength interferometry

Measurement of the free electron line density in a spherical theta-pinch plasma target by single wavelength interferometry

Determination of Hydrogen Density by Swift Heavy Ions

Compression of an accelerated plasma cloud in a cone

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