Threshold for Thermal Ionization of an Aluminum Surface by Pulsed Megagauss Magnetic Field

Awe, T. J.; Bauer, Bruno; Fuelling, S.; Siemon, R. E.

doi:10.1103/physrevlett.104.035001

Cited by 42 publications

(17 citation statements)

References 21 publications

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“…As was shown in Ref. 23, the appearance of this signal is consistent with the formation of thermal plasma with a temperature above $2 eV. Since the time of plasma formation in Cu was observed to occur at 65 ns as compared to 45 ns for Ni, we may infer that liner conductivity is important in plasma formation.…”

Section: B Euv Emission and Plasma Formationsupporting

confidence: 82%

Study of instability formation and EUV emission in thin liners driven with a compact 250 kA, 150 ns linear transformer driver

et al. 2014

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A compact linear transformer driver, capable of producing 250 kA in 150 ns, was used to study instability formation on the surface of thin liners. In the experiments, two different materials, Cu and Ni, were used to study the effect of the liner's resistivity on formation and evolution of the instabilities. The dimensions of the liners used were 7 mm height, 1 mm radius, and 3 lm thickness. Laser probing and time resolved extreme ultraviolet (EUV) imaging were implemented to diagnose instability formation and growth. Time-integrated EUV spectroscopy was used to study plasma temperature and density. A constant expansion rate for the liners was observed, with similar values for both materials. Noticeable differences were found between the Cu and Ni instability growth rates. The most significant perturbation in Cu rapidly grows and saturates reaching a limiting wavelength of the order of the liner radius, while the most significant wavelength in Ni increases slowly before saturating, also at a wavelength close to the liner radius. Evidence suggests that the instability observed is the well-known m ¼ 0 MHD instability. However, upon comparing the instability evolution of Cu and Ni, the importance of the resistivity on the seeding mechanism becomes evident. A comparison of end-on and side-on EUV emission possible indicates the formation of precursor plasma, where it has been estimated using EUV spectroscopy that the precursor plasma temperature is approximately 40 eV with ion density of order 10 19 cm À3 , for both materials. V C 2014 AIP Publishing LLC. [http://dx.

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Section: B Euv Emission and Plasma Formationsupporting

confidence: 82%

Study of instability formation and EUV emission in thin liners driven with a compact 250 kA, 150 ns linear transformer driver

et al. 2014

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“…Most of the attention thus far has been on the study of single mode 8 and multi-mode 9 magneto Rayleigh-Taylor (MRT) instability growth. 10 However, it is also important to understand the physics that precedes MRT instability growth including the physical processes of surface initiation [11][12][13] as current first begins to flow in a liner. In this context, the striation form of the electrothermal instability (referred to subsequently as just electrothermal instabilities) is particularly important since the wavevector of the instability allows for coupling to MRT instability growth.…”

Section: Introductionmentioning

confidence: 99%

Simulations of electrothermal instability growth in solid aluminum rods

Peterson

Sinars

et al. 2013

Physics of Plasmas

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A recent publication [K. J. Peterson et al., Phys. Plasmas 19, 092701 (2012)] describes simulations and experiments of electrothermal instability growth on well characterized initially solid aluminum and copper rods driven with a 20 MA, 100 ns rise time current pulse on Sandia National Laboratories Z accelerator. Quantitative analysis of the high precision radiography data obtained in the experiments showed excellent agreement with simulations and demonstrated levels of instability growth in dense matter that could not be explained by magneto-Rayleigh-Taylor instabilities alone. This paper extends the previous one by examining the nature of the instability growth in 2D simulations in much greater detail. The initial instability growth in the simulations is shown via several considerations to be predominantly electrothermal in nature and provides a seed for subsequent magneto-Rayleigh-Taylor growth.

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“…At lower temperatures and higher densities, one may enter a regime of a nonideal plasma [22] where thermal particle energies would become smaller than the Coulomb interaction energies. This regime usually corresponds to an early stage of the discharge, where the melting and evaporation of the conductor begin [23], [24]. We will not dwell on these issues.…”

Section: General Characterization Of the Z -Pinch Plasmas A Collmentioning

confidence: 99%

Characterizing the Plasmas of Dense $Z$ -Pinches

Ryutov

2015

IEEE Trans. Plasma Sci.

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This mini-tutorial summarizes the plasma characteristics important for the Z-pinch research, with an emphasis on high-density collisional plasmas. It begins with the discussion of the most basic plasma properties related to collisionality and magnetization and then proceeds to more complex phenomena associated with magnetic field evolution in a highly dynamical plasma. Plasma transport properties are discussed mostly in conjunction with the Magnetized Liner Inertial Fusion concept. Issues of interplay of the classical and anomalous transport in a plasma whose pressure is higher than the magnetic pressure are elucidated. Differences in magnetic reconnection in weakly versus highly collisional plasmas are discussed. Kinetic effects and the role of microturbulence are mentioned in conjunction with the formation of high-energy tails in the particle distribution functions and the generation of particle beams. The discussion is based on the order-of-magnitude estimates suitable for initial orientation in the problem. The two appendixes contain some auxiliary material.

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Threshold for Thermal Ionization of an Aluminum Surface by Pulsed Megagauss Magnetic Field

Cited by 42 publications

References 21 publications

Study of instability formation and EUV emission in thin liners driven with a compact 250 kA, 150 ns linear transformer driver

Study of instability formation and EUV emission in thin liners driven with a compact 250 kA, 150 ns linear transformer driver

Simulations of electrothermal instability growth in solid aluminum rods

Characterizing the Plasmas of Dense $Z$ -Pinches

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