Electrode contaminant plasma effects in 
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-A 
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 pinch accelerators

Welch, D. R.; Bennett, Nichelle; Genoni, T. C.; Rose, D. V.; Thoma, C.; Miller, Carol; Stygar, W. A.

doi:10.1103/physrevaccelbeams.22.070401

Cited by 33 publications

(11 citation statements)

References 27 publications

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“…More recently, Refs. [54] and [13] modeled more realistic MITLs with dynamic cathode plasmas and found that the combination of plasma and sheath instabilities enhanced the plasma expansion into the MITL gap. The instabilities modeled in Ref.…”

Section: Fig 6 the Measured And Simulated Currents In The Stack Andmentioning

confidence: 99%

“…To encompass the radial feeds in realistic models of Z, the volumes in the simulation encompass 5 × 10 4 cm 3 , with field energy densities from a few J=cm 3 to nearly one MJ=cm 3 at the load. The simulations use a magnetic implicit particle and field solution [12,13] which simultaneously relax the time constraints of the cyclotron and plasma frequencies, enabling ω c Δt > 1 and ω p Δt > 1. An adaptive time step and particle management [14] enable both the time step and macroparticle count to adjust to the plasma generated in the unified electrode plasma model [13].…”

Section: Introductionmentioning

confidence: 99%

“…The simulations use a magnetic implicit particle and field solution [12,13] which simultaneously relax the time constraints of the cyclotron and plasma frequencies, enabling ω c Δt > 1 and ω p Δt > 1. An adaptive time step and particle management [14] enable both the time step and macroparticle count to adjust to the plasma generated in the unified electrode plasma model [13]. With these algorithms and sufficient resolution, the simulations are able to span the range of physical processes that occur in a Z shot, including vacuum pulse propagation, charged-particle emission, magnetically insulation current flow, and plasma formation and expansion.…”

Section: Introductionmentioning

confidence: 99%

“…The electrode plasmas from which the electrons and ions are drawn are created from desorbed surface contaminants, as modeled as in Refs. [11,13]. A realistic circuit model [9] provides the driving pulse so simulated currents may be validated against data.…”

Section: Introductionmentioning

confidence: 99%

“…The electrode physics detailed in Ref. [13] creates conditions for dense current-carrying plasma formation and expansion into the AK gap. The impact of plasma expansion will be greatest at radii interior to the current adder, where the current densities and surface temperatures are highest.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Current transport and loss mechanisms in the Z accelerator

Bennett

Welch

Jennings

et al. 2019

Phys. Rev. Accel. Beams

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A challenge for the TW-class accelerators driving Z-pinch experiments, such as Sandia National Laboratories' Z machine, is to efficiently couple power from multiple storage banks into a single multi-MA transmission line. The physical processes that lead to current loss are identified in new large-scale, multidimensional simulations of the Z machine. Kinetic models follow the range of physics occurring during a pulse, from vacuum pulse propagation to charged-particle emission and magnetically-insulated current flow to electrode plasma expansion. Simulations demonstrate that current is diverted from the load through a combination of standard transport (uninsulated charged-particle flows) and anomalous transport. Standard transport occurs in regions where the electrode current density is a few 10 4 − 10 5 A=cm 2 and current is diverted from the load via transport without magnetic insulation. In regions with electrode current density > 10 6 A=cm 2 , electrode surface plasmas develop velocity-shear instabilities and a Hall-fieldrelated transport which scales with electron density and may, therefore, lead to increased current loss.

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Section: Fig 6 the Measured And Simulated Currents In The Stack Andmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Current transport and loss mechanisms in the Z accelerator

Bennett

Welch

Jennings

et al. 2019

Phys. Rev. Accel. Beams

Self Cite

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A software environment for effective reliability management for pulsed power design

Robinson

Drake

Swan

et al. 2021

Reliability Engineering & System Safety

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One-dimensional theory and simulations of the dynamic Z-pinch

2020

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The dynamical formation of a Z-pinch in the strong-shock limit is studied in this paper using one-dimensional (1D) simulations of a two-temperature magnetohydrodynamic model. The classic 1D picture consists of three stages: run-in, reflected-shock, and expansion. The special case of a constant current I and uniform gas fill, which are approximate conditions of the pinch-formation stage in a dense plasma focus, is examined in detail. Time-profiles for the shock-front and piston positions during the run-in stage are compared with some of the commonly used 0D models from the literature. Some practical improvements to these models are presented here and it is shown that this model gives the best agreement with results from the simulations. Maximum compression of the plasma is achieved when the reflected shock from the axis meets the incoming current layer. The ratio of the plasma radius at this time with respect to its initial radius is found from the simulations to be rp/R≈1/8 using 5/3 for the adiabatic coefficient γ. The pressure and temperature of the compressed plasma are found to peak a short time after maximum compression due to the inability of the reflected shock to completely stagnate the incoming plasma driven by the converging current layer. The variation of the results with a finite dI/dt and for different values of γ is presented.

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Electrode contaminant plasma effects in 107 -A Z pinch accelerators

Cited by 33 publications

References 27 publications

Current transport and loss mechanisms in the Z accelerator

Current transport and loss mechanisms in the Z accelerator

A software environment for effective reliability management for pulsed power design

One-dimensional theory and simulations of the dynamic Z-pinch

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