Energy loss to conductors operated at lineal current densities<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mo>≤</mml:mo><mml:mn>10</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>MA</mml:mi><mml:mo>/</mml:mo><mml:mi>cm</mml:mi></mml:math>: Semianalytic model, magnetohydrodynamic simulations, and experiment

Stygar, W. A.; Rosenthal, S.E.; Ives, H.C.; Wagoner, T. C.; Allshouse, G.O.; Androlewicz, K. E.; Donovan, G.L.; Fehl, D. L.; Fresé, Michael; Gilliland, T. L.; Johnson, M.F.; Mills, J. A.; Reisman, D. B.; Reynolds, P.; Speas, Christopher; Spielman, R. B.; Struve, K. W.; Toor, A.; Waisman, E.

doi:10.1103/physrevstab.11.120401

Cited by 27 publications

(17 citation statements)

References 19 publications

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“…3. For this calculation, the circuit parameters have been scaled to represent the equivalent ten-cavity parameters [43]. The peak value and overall waveform shape of the downstream power obtained from the 3D simulation model is in good agreement with the circuit calculation.…”

Section: Ten-cavity Accelerator Modelmentioning

confidence: 59%

“…The individual cavities are triggered sequentially, with 6.6 ns between cavity firings to deliver the optimum peak power and rise time to the load [43]. Figure 8 shows the load power as a function of time for the 3D EM simulation model (red curve).…”

Section: Ten-cavity Accelerator Modelmentioning

confidence: 99%

“…The development of these expressions follows the more general analysis of energy loss in current-carrying conductors that is given in Ref. [43].…”

Section: Appendix A: a Time-dependent Current Loss Model For A Ferrommentioning

confidence: 99%

“…We first develop an expression for the effective resistance due to the cores. The total energy loss (per unit surface area of core material) W t is assumed to be the sum of four components [43]:…”

Section: Appendix A: a Time-dependent Current Loss Model For A Ferrommentioning

confidence: 99%

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Circuit models and three-dimensional electromagnetic simulations of a 1-MA linear transformer driver stage

Rose

Miller

Welch

et al. 2010

Phys. Rev. ST Accel. Beams

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A 3D fully electromagnetic (EM) model of the principal pulsed-power components of a high-current linear transformer driver (LTD) has been developed. LTD systems are a relatively new modular and compact pulsed-power technology based on high-energy density capacitors and low-inductance switches located within a linear-induction cavity. We model 1-MA, 100-kV, 100-ns rise-time LTD cavities [A. A. Kim et al., Phys. Rev. ST Accel. Beams 12, 050402 (2009)] which can be used to drive z-pinch and material dynamics experiments. The model simulates the generation and propagation of electromagnetic power from individual capacitors and triggered gas switches to a radially symmetric output line. Multiple cavities, combined to provide voltage addition, drive a water-filled coaxial transmission line. A 3D fully EM model of a single 1-MA 100-kV LTD cavity driving a simple resistive load is presented and compared to electrical measurements. A new model of the current loss through the ferromagnetic cores is developed for use both in circuit representations of an LTD cavity and in the 3D EM simulations. Good agreement between the measured core current, a simple circuit model, and the 3D simulation model is obtained. A 3D EM model of an idealized ten-cavity LTD accelerator is also developed. The model results demonstrate efficient voltage addition when driving a matched impedance load, in good agreement with an idealized circuit model.

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Section: Ten-cavity Accelerator Modelmentioning

confidence: 59%

Section: Ten-cavity Accelerator Modelmentioning

confidence: 99%

“…The development of these expressions follows the more general analysis of energy loss in current-carrying conductors that is given in Ref. [43].…”

Section: Appendix A: a Time-dependent Current Loss Model For A Ferrommentioning

confidence: 99%

Section: Appendix A: a Time-dependent Current Loss Model For A Ferrommentioning

confidence: 99%

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Circuit models and three-dimensional electromagnetic simulations of a 1-MA linear transformer driver stage

Rose

Miller

Welch

et al. 2010

Phys. Rev. ST Accel. Beams

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“…Within the high-current-density regions of the vacuum convolute and inner MITL we model energy lost to the conductors due to ohmic heating, magnetic diffusion, and conductor motion as described in Ref. [30].…”

Section: E Energy Lost To Conductors At High Lineal Current Densitiesmentioning

confidence: 99%

Transmission-line-circuit model of an 85-TW, 25-MA pulsed-power accelerator

Hutsel

Corcoran

Cuneo

et al. 2018

Phys. Rev. Accel. Beams

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We have developed a physics-based transmission-line-circuit model of the Z pulsed-power accelerator. The 33-m-diameter Z machine generates a peak electrical power as high as 85 TW, and delivers as much as 25 MA to a physics load. The circuit model is used to design and analyze experiments conducted on Z. The model consists of 36 networks of transmission-line-circuit elements and resistors that represent each of Zs 36 modules. The model of each module includes a Marx generator, intermediate-energy-storage capacitor, laser-triggered gas switch, pulse-forming line, self-break water switches, and tri-plate transmission lines. The circuit model also includes elements that represent Zs water convolute, vacuum insulator stack, four parallel outer magnetically insulated vacuum transmission lines (MITLs), double-post-hole vacuum convolute, inner vacuum MITL, and physics load. Within the vacuum-transmission-line system the model conducts analytic calculations of current loss. To calculate the loss, the model simulates the following processes: (i) electron emission from MITL cathode surfaces wherever an electric-field threshold has been exceeded; (ii) electron loss in the MITLs before magnetic insulation has been established; (iii) flow of electrons emitted by the outer-MITL cathodes after insulation has been established; (iv) closure of MITL anode-cathode (AK) gaps due to expansion of cathode plasma; (v) energy loss to MITL conductors operated at high lineal current densities; (vi) heating of MITL-anode surfaces due to conduction current and deposition of electron kinetic energy; (vii) negative-space-charge-enhanced ion emission from MITL anode surfaces wherever an anode-surface-temperature threshold has been exceeded; and (viii) closure of MITL AK gaps due to expansion of anode plasma. The circuit model is expected to be most accurate when the fractional current loss is small. We have performed circuit simulations of 52 Z experiments conducted with a variety of accelerator configurations and load-impedance time histories. For these experiments, the apparent fractional current loss varies from 0% to 20%. Results of the circuit simulations agree with data acquired on 52 shots to within 2%.

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Magnetic field measurements via visible spectroscopy on the Z machine

Gómez

Hansen

Peterson

et al. 2014

Review of Scientific Instruments

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Sandia's Z Machine uses its high current to magnetically implode targets relevant to inertial confinement fusion. Since target performance is highly dependent on the applied drive field, measuring magnetic field at the target is essential for accurate simulations. Recently, the magnetic field at the target was measured through splitting of the sodium 3s-3p doublet at 5890 and 5896 Å. Spectroscopic dopants were applied to the exterior of the target, and spectral lines were observed in absorption. Magnetic fields in excess of 200 T were measured, corresponding to drive currents of approximately 5 MA early in the pulse.

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Energy loss to conductors operated at lineal current densities≤10 MA/cm: Semianalytic model, magnetohydrodynamic simulations, and experiment

Cited by 27 publications

References 19 publications

Circuit models and three-dimensional electromagnetic simulations of a 1-MA linear transformer driver stage

Circuit models and three-dimensional electromagnetic simulations of a 1-MA linear transformer driver stage

Transmission-line-circuit model of an 85-TW, 25-MA pulsed-power accelerator

Magnetic field measurements via visible spectroscopy on the Z machine

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