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High-current discharge channel contraction in high density gas
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10.1063/1.3662053
/content/aip/journal/pop/18/12/10.1063/1.3662053
http://aip.metastore.ingenta.com/content/aip/journal/pop/18/12/10.1063/1.3662053
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Scheme and construction of the discharge chamber: 1—casing; 2—bandage; 3—current collector; 4—current input; 5—isolation; 6—cathode; 7—anode; 8—diaphragm; 9—nozzle; 10—buffer chamber with x-ray detector; 11—igniting wire.

Image of FIG. 2.
FIG. 2.

Discharge chamber with attached units for registration of x-ray radiation.

Image of FIG. 3.
FIG. 3.

Discharge in hydrogen under the initial pressure P 0 of 5 MPa in 12-mm-long discharge gap with 6-mm-diameter flat tungsten electrodes with embedded energy into the arc of 60 kJ: (a) Optical streak image, (b) waveforms of the current J and voltage V, (c) time dependencies of the brightness B at the center of the channel and the light diameter D of discharge channel corresponding to relative brightness 0.7 from maximal channel brightness; 1—igniting wire explosion; 2—brightness decreasing, 3—channel contraction.

Image of FIG. 4.
FIG. 4.

Discharge in hydrogen under the initial pressure P 0 of 32 MPa in 20-mm-long discharge gap with 20-mm-diameter hemispheric steel electrodes with embedded energy into the arc of 500 kJ: (a) Optical streak image, (b) waveforms of the current J and voltage V, and (c) time dependence of the brightness temperature T br and the light diameter D 0.3 and D 0.7 of the discharge channel corresponding to relative brightness 0.3 and 0.7 from maximal channel brightness, respectively; 1—igniting wire explosion, 2—brightness decreasing, and 3—channel contraction.

Image of FIG. 5.
FIG. 5.

Discharge in hydrogen under the initial pressure P 0 of 5 MPa in a 10-mm-long discharge gap with 20-mm-diameter conical steel electrodes with embedded energy into the arc of 300 kJ; (a) Current J and voltage V; (b) x-ray signal Xray-10 μm with 10 μm-thickness of Al-foil filter on sensor; 1—wire explosion, 2—channel contraction.

Image of FIG. 6.
FIG. 6.

Fragments of the current J and voltage V oscillograms and the x-ray signals near the instant of the maximal channel contraction; (a) and (b) discharge in hydrogen under the initial pressure P 0 of 7 MPa in a 10-mm-long discharge gap with 20-mm-diameter conical steel electrodes with embedded energy into the arc of 150 kJ; (c) and (d) discharge in hydrogen under the initial pressure P 0 of 7 MPa in a 10-mm-long discharge gap with 20-mm-diameter conical steel electrodes with embedded energy into the arc of 260 kJ; (a) and (c) current J and voltage V; (b) and (d) x-ray signals: Xray-10 μm and Xray-18 μm—signals with 10 μm- and 18 μm-thickness of Al-foil filters on sensors, respectively; 1—x-ray flash instant.

Image of FIG. 7.
FIG. 7.

Current curves for discharges in hydrogen at P 0 of 7 MPa for steel electrodes and copper igniting wire: (a) discharge chamber diameter is of 63 mm; (b) Ø 55 mm; (c) Ø 43 mm; 1—wire explosion and current pause stage; 2,3,4—time instants of more characteristic feature on current curves; current amplitudes of (a), (b), and (c) are equal, but curves (a) and (c) are shifted for visual clearness. Interelectrode gap is 10 mm.

Image of FIG. 8.
FIG. 8.

Dependence of the brightness temperature T br of the discharge channel with current amplitude J A of 1350 ÷ 1450 kA in 10-mm-long discharge gap with 20-mm-diameter hemispheric steel electrodes at the middle of the discharge gap versus the time under various initial pressures P 0 of the hydrogen: 1 = 5 MPa; 2 = 15 MPa; 3 = 32 MPa.

Image of FIG. 9.
FIG. 9.

Dependence of the maximal brightness temperature T brMax of the discharge channel with current amplitude J A of 1350 ÷ 1450 kA with 20-mm-diameter hemispheric steel electrodes versus the hydrogen initial pressure P 0: 1—solid vertical segments and curve correspond to the 10-mm-long discharge gap; 2—vertical segments and curve in dots correspond to the 20-mm-long discharge gap.

Image of FIG. 10.
FIG. 10.

Dependence of the critical current value J exp versus the hydrogen initial pressure P 0 for discharges with steel electrodes; 1—black squares and solid line correspond to values of the critical current obtained by decreasing of the discharge channel brightness; 2—white squares and line in dots correspond to values of the critical current obtained by peculiarities on the current and voltage curves and by burst of the x-ray signal.

Image of FIG. 11.
FIG. 11.

Light diameter of the discharge channel corresponding to relative brightness versus the time for the experiment in Fig. 4: 1 = 0.3 from maximal channel brightness; 2 = 0.7; 3 = 0.9.; 4 and 5 = markers corresponding to markers 2 and 3 in Fig. 4.

Image of FIG. 12.
FIG. 12.

Dependence of the efficiency η of transmitting the energy from the arc into the gas versus the initial pressure P 0 for discharges with steel electrodes: 1—the solid curve and black squares correspond to the energy (embedded into the arc) larger than 300 kJ; 2—the curve in dots and white squares corresponds to the case with embedded energy lower than 300 kJ; 3—the curve in dashes corresponds to the case when the embedded energy would be constant under growth of density of the quanta energy, which are responsible for the gas heating.

Image of FIG. 13.
FIG. 13.

Dependence of the efficiency η of transmitting the energy from the arc into the gas versus the energy embedded into the arc for discharges with steel electrodes under the initial pressure P 0 of 15 ÷ 35 MPa.

Image of FIG. 14.
FIG. 14.

The hemispheric steel electrode (a) before and (b) after the experiment; 1—the hole for igniting wire installations.

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/content/aip/journal/pop/18/12/10.1063/1.3662053
2011-12-14
2014-04-18
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: High-current discharge channel contraction in high density gas
http://aip.metastore.ingenta.com/content/aip/journal/pop/18/12/10.1063/1.3662053
10.1063/1.3662053
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