Magnetic insulation in a curved vacuum transmission line

Luo, Wei; Wang, Hongguang; Liu, Chunliang; Guo, Fan; Zhang, Lei; Gu, Yu; Zhang, Jianwei

doi:10.1063/1.5085507

Cited by 6 publications

(2 citation statements)

References 37 publications

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“…Consequently, the emitted electron current in regions c and d is almost equal to that near the transitions, whereas the magnetic fields near the transitions are higher than those far away from the transitions (regions c and d). Therefore, the emitted electrons are not well magnetically insulated in regions c and d due to the weak magnetic fields [12].…”

Section: Pic Simulation Results and Analysismentioning

confidence: 99%

“…Unlike the vacuum insulator stacks separating the MITLs from the water lines and drivers in conventional systems, coaxial-disk transitions connect the MITLs to the drivers and transfer the combined pulsed power from tens of drivers to the disk MITLs under vacuum [10]. However, the non-uniform structure of the coaxial-disk transitions can lead to non-uniform magnetic fields and abrupt variation of the MITL impedance, which results in disturbed electron flow and current loss [11,12]. Previous research under the JUPITER and LMF projects suggests a total current loss of approximately 10%-15% in long MITLs due to front pulse erosion and losses in the transition region due to magnetic nulls [6,13].…”

Section: Introductionmentioning

confidence: 99%

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Investigation on current loss of high-power vacuum transmission lines with coaxial-disk transitions by particle-in-cell simulations

Luo¹,

ZHANG²,

LI³

et al. 2021

Plasma Sci. Technol.

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Coaxial-disk transitions can generate non-uniform magnetic fields and abrupt impedance variations in magnetically insulated transmission lines (MITLs), resulting in disturbed electron flow and non-negligible current loss. In this paper, 3D particle-in-cell simulations are conducted with UNPIC-3d to investigate the current loss mechanism and the influence of the input parameters of the coaxial-disk transition on current loss in an MITL system. The results reveal that the magnetic field non-uniformity causes major current loss in the MITL after the coaxialdisk transition, and the non-uniformity decreases with the distance away from the transition. The uniformity of the magnetic field is improved when increasing the number of feed lines of a linear transformer driver-based accelerator with coaxial-disk transitions. The number of input feed lines should be no less than four in the azimuthal distribution to obtain acceptable uniformity of the magnetic field. To make the ratio of the current loss to the total current of the accelerator less than 2% at peak anode current, the ratio of the current in each feed line to the total current should be no less than 8%.

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Section: Pic Simulation Results and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation on current loss of high-power vacuum transmission lines with coaxial-disk transitions by particle-in-cell simulations

Luo¹,

ZHANG²,

LI³

et al. 2021

Plasma Sci. Technol.

Self Cite

View full text Add to dashboard Cite

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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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Theoretical model for magnetically insulated flow with both negative and positive ions

Luo

Qiang

Zhang

et al. 2019

Journal of Applied Physics

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Negative and positive ions crossing the anode-cathode gap of a magnetically insulated transmission line (MITL) can cause non-negligible current loss and energy deposition on the electrodes, which may lead to the formation of anode plasma and the growth of cathode plasma. Furthermore, gap closure could occur due to the expansion of cathode plasma and anode plasma. In this paper, a model for magnetic insulation of both negative ion flow and positive ion flow is developed. The operating voltage V of the MITL is expressed as a function of the total current I0 and the boundary current Ib. The total current and the boundary current of the MITL are derived at saturated and self-limited flows, respectively. In addition, particle-in-cell simulations are implemented for the validation of the theoretical model. The thickness and density of the magnetically insulated ion layers are analyzed, and an empirical expression for space charge factor g is obtained through simulation results. This work extends the understanding of magnetically insulated ion flow in MITLs.

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Magnetic insulation in a curved vacuum transmission line

Cited by 6 publications

References 37 publications

Investigation on current loss of high-power vacuum transmission lines with coaxial-disk transitions by particle-in-cell simulations

Investigation on current loss of high-power vacuum transmission lines with coaxial-disk transitions by particle-in-cell simulations

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

Theoretical model for magnetically insulated flow with both negative and positive ions

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