Multiple-wire array load for high-power pulsed generators

Stallings, C.; Nielsen, K.; Schneider, R.

doi:10.1063/1.89121

Cited by 71 publications

(15 citation statements)

References 5 publications

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“…Interest in studying nanosecond explosions of wires has increased in the last 15-20 years since the successful experiments carried out on the Z facility [67] in which record soft X-ray yields (over 1.5 MJ/pulse) were achieved. A wire array is a cylindrical structure designed as a "squirrel wheel" [66]- [70], [97] with the wires spaced by (2π R wa /N wa ), where R wa is the radius of the wire array and N wa is the number of wires in the array. The (maximum) magnetic induction at the surface of an individual wire is given by B w = (μ 0 I wa /2πr w N wa ), where I wa is the current through the wire array and r w is the wire radius, and the maximum induction of the collective field of the wire array is given by B wa ≈ (μ 0 I wa /2π R wa ).…”

Section: B Classification Of We Modesmentioning

confidence: 99%

Wire Explosion in Vacuum

Oreshkin

Baksht

2020

IEEE Trans. Plasma Sci.

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This article presents a review of experimental and theoretical studies devoted to the processes that occur during explosions of wires in vacuum when the current densities in the wire are of the order of 10 8 A/cm 2 and the current density rise rates are no less than 10 15 A/(cm 2 • s). The theoretical background is focused on the transformation of the wire metal into ionized plasma. In particular, the basic physical notions used to describe wire explosions (WEs; state diagram, current action integral, and metal conductivity changes in phase transitions) are given; magnetohydrodynamic equations are described which are used to simulate WEs, and the simulation predictions are discussed together with their reliability. Extensive experimental data on WEs in vacuum are presented which made it possible to describe the corona and core formation and the development of electrothermal instabilities in the core. The data on the energy deposited in a wire exploding in vacuum reported by different authors are compared. In conclusion, problems are discussed that require additional experimental investigations, namely, the role of metastable states in a WE and the mechanism by which the core is shunted.

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Section: B Classification Of We Modesmentioning

confidence: 99%

Wire Explosion in Vacuum

Oreshkin

Baksht

2020

IEEE Trans. Plasma Sci.

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“…5,6 Quite soon the radiation performance of the Z pinch as a radiation source has been significantly improved by replacing a single wire with a cylindrical array of wires. 7,8 With the eminent progress in the development of multi-MA current accelerators the focus of the Z-pinch study shifted to the implosions of high-wire-number wire array loads ͑up to 300 wires at 20 MA Z current accelerator 9 ͒.…”

Section: Introductionmentioning

confidence: 99%

Magnetostatic and magnetohydrodynamic modeling of planar wire arrays

et al. 2008

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For the past 2 years the planar wire array loads have proven their ability to create powerful x-ray radiation sources at the pulsed power facilities with the current level ranging from 1to3MA. Several key features of the implosion and ablation dynamics of the planar wire arrays distinguish them from the wire arrays of the conventional cylindrical design. The uneven current partition through the array wires in planar geometry results in a significant difference between the ablation rates of the outermost and the innermost array wires. This difference is even higher in a double row planar array geometry. According to the three-dimensional magnetohydrodynamic simulations the effect of the delayed ablation of the inner array wires can result in effective mitigation of the Rayleigh–Taylor instability modes. The high number (200–300) of wires in a cylindrical array is preferable to ensure fine azimuthal symmetry of an array implosion. However this requirement is not a great concern for the planar wire array loads, which implode along the plane of wires. Hence, the low-wire-number planar array loads are naturally optimized for the Z-pinch experiments at short pulse (100ns) 1MA facilities. The application of planar wire array loads at high current accelerators is attractive for the purposes of the inertial confinement fusion because of the relative compactness of these loads and their potential for radiation pulse shaping.

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“…The first plasma loads driven on CESZAR were wire array Z pinches. Since first introduced over 40 years ago [34], wire array Z pinches have been studied as a powerful source of x rays [35][36][37]. Two advantages of wire arrays are that the initial load mass distribution is well defined and that it can be adjusted easily by changing the number and material of the wires.…”

Section: A Wire Array Z Pinchmentioning

confidence: 99%

MA-class linear transformer driver for Z -pinch research

Conti

Valenzuela

Fadeev

et al. 2020

Phys. Rev. Accel. Beams

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A linear transformer driver (LTD) generator capable of delivering up to 0.9 MA current pulses with 160 ns rise time has been assembled and commissioned at University of California San Diego. The machine is an upgrade of the LTD-III pulser from Sandia National Laboratories, consisting of 40 capacitors and 20 spark gap switches, arranged in a 20-brick configuration. The driver was modified with the addition of a new trigger system, active premagnetization of the inductive cores, a vacuum chamber with multiple diagnostic ports, and a vacuum power feed to couple the driver to plasma loads. The new machine is called compact experimental system for Z-pinch and ablation research (CESZAR). The driver has a maximum bipolar charge voltage of AE100 kV, but for reliability and testing, and to reduce the risk of damage to components, the machine was operated at AE60 kV, producing 550 kA peak currents with a rise time of 170 ns on a 3.5 nH short circuit. While the peak current is scaled down due to the reduced charge voltage, the pulse shape and circuit parameters are close to the results of the cavity and power feed models but suggest a slightly higher inductance than predicted. The machine was then used to drive wire array Z-pinch and gas puff Z-pinch experiments as initial dynamic plasma loads. The evolution of the wire array Z pinch is consistent with the general knowledge of this kind of experiment, featuring wire ablation and stagnation of the precursor plasma on axis. The gas puff Z pinches were configured as a single, hollow argon gas shell, in preparation for more structured gas puff targets such as multispecies, multishell implosions. The implosion dynamics agree generally with 1D magnetohydrodynamics simulation results, but large zippering and magneto-Rayleigh-Taylor instabilities are observed. The CESZAR load region was designed to accommodate many load types to be driven by the machine, which makes it a versatile platform for studying Z-pinch plasmas. The completion of the CESZAR driver allows plasma experiments on energy coupling from LTD machines to plasma loads, instability mitigation techniques and magnetic field distributions in Z pinches, and interface dynamics in multispecies implosions.

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Multiple-wire array load for high-power pulsed generators

Cited by 71 publications

References 5 publications

Wire Explosion in Vacuum

Wire Explosion in Vacuum

Magnetostatic and magnetohydrodynamic modeling of planar wire arrays

MA-class linear transformer driver for Z -pinch research

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