Plasma-neutral gas boundary layers

Lehnert, B.

doi:10.1016/0029-554x(75)90107-x

Cited by 18 publications

(7 citation statements)

References 12 publications

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“…According to [43], the ionization layer thickness is given by L nf = [2kT / (µ in ξ (ξ + ξ in ))] 1/2 /n i where ξ is the ionization rate, n i the average ion density and T the average temperature in the ionization layer. Charge exchange rate is taken from [44] and ionization rate as a function of temperature for argon is taken from [45].…”

Section: Late Current Mitigationmentioning

confidence: 99%

“…In order to address these questions, estimates of the thickness of the neutral diffusion and ionization layer at the edge of the background plasma were made. The simplified model described by Lehnert ([51,52]) was used to obtain with such estimates. It distinguishes a number of different edge plasma regimes, one of them being impermeable to neutrals.…”

Section: Late Current Mitigationmentioning

confidence: 99%

See 1 more Smart Citation

Runaway electron beam generation and mitigation during disruptions at JET-ILW

Reux¹,

Plyusnin²,

Alper³

et al. 2015

Nucl. Fusion

111

129

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Disruptions are a major operational concern for next generation tokamaks, including ITER. They may generate excessive heat loads on plasma facing components, large electromagnetic forces in the machine structures and several MA of multi-MeV runaway electrons. A more complete understanding of the runaway generation processes and methods to suppress them is necessary to ensure safe and reliable operation of future tokamaks. Runaway electrons were studied at JET-ILW showing that their generation dependencies (accelerating electric field, avalanche critical field, toroidal field, MHD fluctuations) are in agreement with current theories.

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Section: Late Current Mitigationmentioning

confidence: 99%

Section: Late Current Mitigationmentioning

confidence: 99%

Runaway electron beam generation and mitigation during disruptions at JET-ILW

Reux¹,

Plyusnin²,

Alper³

et al. 2015

Nucl. Fusion

111

129

View full text Add to dashboard Cite

show abstract

“…Within this boundary layer, there are at least two distinct regimes5 each with its own set of properties which can potentially affect the process of synthesis: 1) The outer boundary region where only the slow components perturb the steady state and 2) The inner ionization region where the fast neutrals are present. The former has a more turbulent nature and lower temperature due to the presence of neutrals while the latter because of the flow of transverse electric currents is essentially diamagnetic6 and therefore establishes a strong screening effect which minimizes ion loss.…”

mentioning

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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“…The primary purpose of a cold plasma blanket in a fusion reactor is to prevent high-energy neutrals from hitting the wall of the container and giving rise to sputtering with subsequent impurity influx [1,2].…”

Section: Introductionmentioning

confidence: 99%

“…The ion temperature in the blanket zone must be lower than the sputtering threshold energy of the wall material (~ 200 eV) and the width, A, of the boundary region must exceed the penetration length, L, for charge exchange of highly energetic neutrals from the core of the hot plasma. The last condition is Lehnert's impermeability condition, [ 1 ], nA > nL > 10 1S cm" 2 , where n denotes the plasma density. On the other hand, the heat transport properties of the blanket must be such that the heat incident from the hot plasma core can efficiently be transported across the width of the blanket region resulting in the necessary temperature drop.…”

Section: Introductionmentioning

confidence: 99%