Gas-Insulation of a Hot Plasma

Alfvén, Hannes; Smars, E.A.

doi:10.1038/188801a0

Cited by 75 publications

(17 citation statements)

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“…Achieving such a versatility using a typical thermal plasma is not feasible mainly because of substantial heat conduction via ion loss to the surrounding19 which can in turn alter the kinetics of reaction. Additionally an arc channel developed under the sole effect of Ohmic heating is limited in dimension to the size of the electrode20 and is not homogenous owing to lower collision frequency in the absence of screening.…”

Section: Discussionmentioning

confidence: 99%

Tunable synthesis and in situ growth of silicon-carbon mesostructures using impermeable plasma

Yaghoubi

Mélinon

2013

Sci Rep

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In recent years, plasma-assisted synthesis has been extensively used in large scale production of functional nano- and micro-scale materials for numerous applications in optoelectronics, photonics, plasmonics, magnetism and drug delivery, however systematic formation of these minuscule structures has remained a challenge. Here we demonstrate a new method to closely manipulate mesostructures in terms of size, composition and morphology by controlling permeability at the boundaries of an impermeable plasma surrounded by a blanket of neutrals. In situ and rapid growth of thin films in the core region due to ion screening is among other benefits of our method. Similarly we can take advantage of exceptional properties of plasma to control the morphology of the as deposited nanostructures. Probing the plasma at boundaries by means of observing the nanostructures, further provides interesting insights into the behaviour of gas-insulated plasmas with possible implications on efficacy of viscous heating and non-magnetic confinement.

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Section: Discussionmentioning

confidence: 99%

Tunable synthesis and in situ growth of silicon-carbon mesostructures using impermeable plasma

Yaghoubi

Mélinon

2013

Sci Rep

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“…For Alfvén and Smårs [547] the magnetic pressure was important for confinement, and the surrounding gas was considered as high density gas-insulation. Fälthammar [108] investigated the steady-state cross-field thermal conduction losses of such a Z-pinch, as discussed in section 2.3.…”

Section: Gas-embedded Pinchmentioning

confidence: 99%

A review of the denseZ-pinch

Haines

2011

Plasma Phys. Control. Fusion

388

184

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The Z-pinch, perhaps the oldest subject in plasma physics, has achieved a remarkable renaissance in recent years, following a few decades of neglect due to its basically unstable MHD character. Using wire arrays, a significant transition at high wire number led to a great improvement in both compression and uniformity of the Z-pinch. Resulting from this the Z-accelerator at Sandia at 20 MA in 100 ns has produced a powerful, short pulse, soft x-ray source >230 TW for 4.5 ns) at a high efficiency of ∼15%. This has applications to inertial confinement fusion. Several hohlraum designs have been tested. The vacuum hohlraum has demonstrated the control of symmetry of irradiation on a capsule, while the dynamic hohlraum at a higher radiation temperature of 230 eV has compressed a capsule from 2 mm to 0.8 mm diameter with a neutron yield >3 × 10 11 thermal DD neutrons, a record for any capsule implosion. World record ion temperatures of >200 keV have recently been measured in a stainless-steel plasma designed for Kα emission at stagnation, due, it was predicted, to ion-viscous heating associated with the dissipation of fast-growing short wavelength nonlinear MHD instabilities. Direct fusion experiments using deuterium gas-puffs have yielded 3.9×10 13 neutrons with only 5% asymmetry, suggesting for the first time a mainly thermal source. The physics of wire-array implosions is a dominant theme. It is concerned with the transformation of wires to liquid-vapour expanding cores; then the generation of a surrounding plasma corona which carries most of the current, with inward flowing low magnetic Reynolds number jets correlated with axial instabilities on each wire; later an almost constant velocity, snowplough-like implosion occurs during which gaps appear in the cores, leading to stagnation on the axis, and the production of the main soft-x-ray pulse. These studies have been pursued also with smaller facilities in other laboratories around the world. At Imperial College, conical and radial wire arrays have led to highly collimated tungsten plasma jets with a Mach number of >20, allowing laboratory astrophysics experiments to be undertaken. These highlights will be underpinned in this review with the basic physics of Z-pinches including stability, kinetic effects, and finally its applications.

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“…An applied longitudinal magnetic field serves three purposes: It reduces the energy loss due to heat conduction, it confines the energetic a-particles, and it reduces the radial diffusion velocities. To reduce the heat conduction a strong field seems to be advantageous [5].…”

Section: The Reactor Modelmentioning

confidence: 99%

The temperature profile in a thermonuclear reactor

Verboom

Rem

1973

Nucl. Fusion

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The problem of a steady-state infinitely long plasma cylinder is considered in which nuclear reactions take place. The analysis is restricted to the fully ionized region, but the temperature at the “wall” is sufficiently low, so that nuclear energy is liberated only in the centre. Of all possible nuclear reactions at axis temperature of 108 – 109°K only the D-T reaction is considered (50/50 mixture). The energy is carried away by bremsstrahlung, re-absorption of which is neglected, and by heat conduction to the wall.An externally applied axial magnetic field (between 3 and 10 Tesla at the “wall”) perpendicular to the radial temperature gradient gives rise to a large diamagnetic azimuthal current, as a result of which the pressure at the boundary is much lower than in the centre (e.g. 10−1 and 100 atm, respectively). The fuel supply and the ash removal take place through classical diffusion to and from the “wall” through this low-pressure region.The macroscopic equations are solved for a number of values of the parameters involved. No acceptable solution exists if the helium density in the centre is either too low or too high, but it must be higher than the deuterium-tritium density. Solutions with a power production up to 1 GW per metre length and a plasma radius of up to a few metres are found.

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Gas-Insulation of a Hot Plasma

Cited by 75 publications

References 1 publication

Tunable synthesis and in situ growth of silicon-carbon mesostructures using impermeable plasma

Tunable synthesis and in situ growth of silicon-carbon mesostructures using impermeable plasma

A review of the denseZ-pinch

The temperature profile in a thermonuclear reactor

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