Novel gas-doping technique for local spectroscopic measurements in pulsed-power systems

Arad, R.; Ding, L.; Maron, Y.

doi:10.1063/1.1148791

Cited by 15 publications

(14 citation statements)

References 16 publications

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“…In this approach the plasma is doped by an atomic or ionic beam, the line emission of which can be used for diagnosing the local plasma parameters ͑spectroscopic studies have been made to verify that the doped species densities are sufficiently low to cause no significant effect on the main-plasma properties͒. 30 The spatial resolution along the line of sight is thus determined by the doped column width. Three doping methods are used: a gas doping technique, a surfaceflashover method for producing dopants of solid materials, 17 and an additional method in which the dopant is produced by a pulsed laser beam aimed at a window with its front or back surface coated by a thin layer ͑ϳ1 m͒ of a selected material.…”

Section: Methodsmentioning

confidence: 99%

Plasma dynamics in pulsed strong magnetic fields

et al. 2004

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Recent investigations of the interaction of fast-rising magnetic fields with multi-species plasmas at densities of 1013–1015 cm−3 are described. The configurations studied are planar or coaxial interelectrode gaps pre-filled with plasmas, known as plasma opening switches. The diagnostics are based on time-dependent, spatially resolved spectroscopic observations. Three-dimensional spatial resolution is obtained by plasma-doping techniques. The measurements include the propagating magnetic field structure, ion velocity distributions, electric field strengths, and non-Maxwellian electron energy distribution across the magnetic field front. It is found that the magnetic field propagation velocity is faster than expected from diffusion. The magnetic field evolution cannot be explained by the available theoretical treatments based on the Hall field (that could, in principle, explain the fast field propagation). Moreover, detailed observations reveal that magnetic field penetration and plasma reflection occur simultaneously, leading to ion-species separation, which is also not predicted by the available theories. A possible mechanism that is based on the formation of small-scale density fluctuations, previously formulated for astrophysical plasmas, may explain these results.

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Section: Methodsmentioning

confidence: 99%

Plasma dynamics in pulsed strong magnetic fields

et al. 2004

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“…The gas doping arrangement, 31 consisting of a fast gas valve, a nozzle, and a skimmer, is mounted below the cathode. The gas density can be varied from 10 13 to 10 15 cm −3 and the FWHM of the gas beam perpendicular to its injection direction can be varied from 1 to 2 cm.…”

Section: Experimental Arrangementmentioning

confidence: 99%

“…In the present experiments, the plasma doping techniques 31,32 were improved to allow for doping gaseous as well as solid elements, and, combined with the planar geometry, yielded higher spatial resolution in the magnetic-fieldpropagation direction. This improvement in resolution, together with the knowledge of the previously obtained plasma composition, 32 allows for a detailed comparison of the ion dynamics and the accelerating magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the ion dynamics in a multispecies plasma under pulsed magnetic fields

et al. 2004

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The interaction between a moving magnetic-field front and a low-collisionality plasma consisting of different ion species is investigated using spatially and temporally resolved spectroscopic techniques. The experiment is carried out in a plasma-opening-switch configuration, in which a current rising to 150 kA in 400 ns is conducted through a plasma that prefills the region between two planar electrodes. Ion-species separation is found to occur, similarly to the results reported for a 80 ns duration plasma-opening-switch experiment of cylindrical geometry, which was not necessarily expected since in the present experiment plasma pushing is more substantial. The separation, in which the light-ion plasma (protons) is reflected while the heavy-ion plasma (carbon) is penetrated by the propagating magnetic-field, is investigated by determining the electron density from the temporal evolution of spectral lines, the nonprotonic ion velocities from line-emission Doppler shifts, and the proton velocity distribution from Doppler shifts of line emissions from hydrogen atoms produced by proton charge exchange. The ion dynamics is shown to be consistent with the acceleration expected from the one-dimensional Hall electric field, based on the previously published magnetic-field and electron density evolutions. Significant acceleration of the nonprotonic ions behind the magnetic-field front is observed. It is found that a significant fraction of the protons acquire a velocity that is more than twice the velocity of the magnetic piston. This phenomenon is shown to result from the time dependence of the accelerating electric field and the broad acceleration region. The lateral motion of the nonprotonic ions is also discussed.

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“…In order to obtain three-dimensional (3-D) spatially resolved measurements, we utilize our recently developed plasma-doping techniques. In this approach, the plasma is locally doped with atoms or ions, the line emission of which can be used for diagnosing the local plasma parameters (spectroscopic studies have been made to verify that the doped species densities are sufficiently low to cause no significant effect on the main-plasma properties [24]). …”

Section: Experimental Setup and Diagnosticsmentioning

confidence: 99%

On the Role of the Plasma Composition in the Magnetic Field Evolution in Plasma Opening Switches

Osin

Doron

Arad

et al. 2004

IEEE Trans. Plasma Sci.

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Abstract-High spatial-and temporal-resolution spectroscopic methods are employed to perform detailed studies of the interaction between the propagating magnetic field and a multi-ion-species plasma. The experiment is performed in a plasma-opening-switch configuration, in which a 150-kA current of 400 ns duration is conducted through a plasma. Recent observations demonstrated a new phenomenon of simultaneous rapid magnetic field penetration into the heavy-ion plasma and specular reflection of the light-ion plasma, leading to ion-species separation. Additionally, noticeable inconsistencies between experimental results and theories were found. The current paper summarizes these recent results and discusses the aspect of the role of the plasma composition in the magnetic field evolution and ion dynamics. In order to systematically investigate the effect of the plasma composition, a method for producing plasmas with controllable compositions, based on spatial species separation and electrode heating, is presented. This method allows for achieving plasmas with varying proton-to-carbon ion ratios, however, at different electron densities. Measurements are described for studying the relation between the magnetic field propagation velocity and the plasma composition and density; however, this relation is not yet satisfactorily clear.Index Terms-Magnetic field-plasma interaction, multi-ion species plasma, plasma devices, plasma spectroscopy.

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Novel gas-doping technique for local spectroscopic measurements in pulsed-power systems

Cited by 15 publications

References 16 publications

Plasma dynamics in pulsed strong magnetic fields

Plasma dynamics in pulsed strong magnetic fields

Investigation of the ion dynamics in a multispecies plasma under pulsed magnetic fields

On the Role of the Plasma Composition in the Magnetic Field Evolution in Plasma Opening Switches

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