Modeling particle emission and power flow in pulsed-power driven, nonuniform transmission lines

Bruner, Nichelle; Genoni, T. C.; Madrid, E. A.; Rose, D. V.; Welch, D. R.; Hahn, Kelly; Leckbee, Joshua J.; Portillo, S.; Oliver, B.V.; Bailey, V.; Johnson, D.L.

doi:10.1103/physrevstab.11.040401

Cited by 29 publications

(21 citation statements)

References 26 publications

(26 reference statements)

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“…The thresholds are a function of the material and its preparation. A typical values for accelerator cathodes range from 150 to 250 kV=cm [9]. The value may be determined by the departure of the transmission line current from their vacuum values, for example when OF exceeds IF.…”

Section: A Simulation Detailsmentioning

confidence: 99%

“…To determine the suitability of the self-magnetic-pinch (SMP) diode [1][2][3][4][5][6] as a radiographic source, an experimental campaign was conducted on Sandia's RITS-6 accelerator [7][8][9] to quantify its shot-toshot variation. The accelerator operated at 4.5 MV and the SMP diode was fielded with changes only to the anodecathode (AK) gap and cathode needle radius (r c ).…”

Section: Introductionmentioning

confidence: 99%

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Shot reproducibility of the self-magnetic-pinch diode at 4.5 MV

Bennett

Crain

Droemer

et al. 2014

Phys. Rev. ST Accel. Beams

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In experiments conducted at Sandia National Laboratories' RITS-6 accelerator, the self-magnetic-pinch diode exhibits significant shot-to-shot variability. Specifically, for identical hardware operated at the same voltage, some shots exhibit a catastrophic drop in diode impedance. A study is underway to identify sources of shot-to-shot variations which correlate with diode impedance collapse. The scope of this report is limited to data collected at 4.5-MV peak voltage and sources of variability which occur away from the diode, such as sheath electron emission and trajectories, variations in pulsed power, load and transmission line alignment, and different field shapers. We find no changes in the transmission line hardware, alignment, or hardware preparation methods which correlate with impedance collapse. However, in classifying good versus poor shots, we find that there is not a continuous spectrum of diode impedance behavior but that the good and poor shots can be grouped into two distinct impedance profiles. In poor shots, the sheath current in the load region falls from 16%-30% of the total current to less than 10%. This result will form the basis of a follow-up study focusing on the variability resulting from diode physics.

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Section: A Simulation Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Shot reproducibility of the self-magnetic-pinch diode at 4.5 MV

Bennett

Crain

Droemer

et al. 2014

Phys. Rev. ST Accel. Beams

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“…The dustbin introduces a further difficulty. It was observed that during the flow, resonant cavity modes develop in it, which interact with the flow, causing unwanted oscillations [13].…”

mentioning

confidence: 99%

“…It was recently shown that the sheath flow is symmetric and regular even for an asymmetric power-generating machine [13]. Even when azimuthal symmetry is assumed, attempts to direct the current around the knob toward the diode resulted in turbulent flow [14].…”

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confidence: 99%

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Regular Charged Particle Flow in Pulsed-Power-Driven Nonuniform Transmission Lines

Leopold

Gad

Leibovitz

et al. 2009

IEEE Trans. Plasma Sci.

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In electron-emitting nonuniform transmission lines at currents sufficient to support magnetic insulation, it is possible to maintain regular Brillouin electron flow by matching the vacuum impedances of various parts of the transmission line and by ensuring adiabatic transition between them. This idea, first demonstrated numerically in the design of the Brillouin diode (BD), is extended to the structure of the pair known as knob and dustbin. Rather than shunting current to the walls, a "designer" knob-dustbin allows regular flow of the entire current to the BD. Index Terms-Brillouin flow, magnetic insulation, transmission line.

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Particle-in-cell simulations of current loss in magnetically insulated transmission line with inductive helical support

et al. 2019

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High inductive helical support provides a solution to controlling the alignment error of inner electrodes in magnetically insulated transmission lines (MITLs). Three-dimensional particle-in-cell simulations were performed to examine the current loss mechanism and the effects of structural parameters on electron flow in an MITL with a helical inductor. An empirical expression related to the ratio of electron current loss to anode current and the ratio of anode current to self-limited current was obtained. Electron current loss caused by helical inductor with different structures was displayed. The results indicate that the current loss in an MITL, near an inductive helical support, comprises both the inductor current and the electron current loss. The non-uniform structure and current of a helical inductor cause an abrupt change in the magnetic field near the helical support, which leads to anomalous behavior and current loss of electron flow. In addition, current loss in the inductive helical-supported MITL is negligible when the inductance of the support is sufficiently high. This work facilitates the estimation of electron current loss caused by the inductive helical support in MITLs.

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Modeling particle emission and power flow in pulsed-power driven, nonuniform transmission lines

Cited by 29 publications

References 26 publications

Shot reproducibility of the self-magnetic-pinch diode at 4.5 MV

Shot reproducibility of the self-magnetic-pinch diode at 4.5 MV

Regular Charged Particle Flow in Pulsed-Power-Driven Nonuniform Transmission Lines

Particle-in-cell simulations of current loss in magnetically insulated transmission line with inductive helical support

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