Breakdown and discharges in dense gases governed by runaway electrons

1996 ◽  
Author(s):  
Leonid P. Babich
Keyword(s):  
Runaway Electrons ◽  
Dense Gases

Runaway of electrons in dense gases and mechanism of generation of high-power subnanosecond beams

Open Physics ◽  
2004 ◽  
Vol 2 (4) ◽  
Author(s):  
Alexey Tkachev ◽  
Sergei Yakovlenko
Keyword(s):  
Electric Fields ◽  
Critical Voltage ◽  
Runaway Electrons ◽  
Local Criterion ◽  
Fast Electrons ◽  
Electron Multiplication ◽  
Dense Gases ◽  
Non Local ◽  
Discharge Gap

AbstractNew understanding of mechanism of the runaway electrons beam generation in gases is presented. It is shown that the Townsend mechanism of the avalanche electron multiplication is valid even for the strong electric fields when the electron ionization friction on gas may be neglected. A non-local criterion for a runaway electron generation is proposed. This criterion results in the universal two-valued dependence of critical voltage U cr on pd for a certain gas (p is a pressure, d is an interelectrode distance). This dependence subdivides a plane (U cr, pd) onto the area of the efficient electron multiplication and the area where the electrons leave the gas gap without multiplication. On the basis of this dependence analogs of Paschen’s curves are constructed, which contain an additional new upper branch. This brunch demarcates the area of discharge and the area of e-beam.The mechanism of the formation of the recently created atomospheric pressure subnanosecond e-beams is discussed. It is shown that the beam of the runaway electrons is formed at an instant when the plasma of the discharge gap approaches to the runaway electrons is formed at an instant when the plasma of the discharge gap approaches to the anode. In this case a basic pulse of the electron beam is formed according to the non-local criterion of the runaway electrons generation.The role of the discharge gap preionization by the fast electrons, emitted from the plasma non-uniformities on the cathode, as well as a propagation of an electron multiplication wave from cathode to anode in a dense gas are considered.

High-Power Subnanosecond Beams of Runaway Electrons Generated in Dense Gases

2005 ◽  
Vol 72 (1) ◽  
pp. 41-67 ◽  
Author(s):  
Victor F Tarasenko ◽  
Sergei I Yakovlenko
Keyword(s):  
High Power ◽  
Runaway Electrons ◽  
Dense Gases

On the electron runaway effect and the generation of high'power subnanosecond beams in dense gases

2006 ◽  
Vol 176 (7) ◽  
pp. 793 ◽  
Author(s):  
Viktor F. Tarasenko ◽  
Sergei I. Yakovlenko
Keyword(s):  
Dense Gases

Historical Background

2018 ◽  
Author(s):  
Klaus Morawetz
Keyword(s):  
Steady State ◽  
Kinetic Theory ◽  
Time Evolution ◽  
Historical Development ◽  
Historical Background ◽  
Quantum Kinetic Theory ◽  
Dense Gases ◽  
Nonequilibrium Phenomena ◽  
Quantum Liquids ◽  
Nonlocal Quantum

The historical development of kinetic theory is reviewed with respect to the inclusion of virial corrections. Here the theory of dense gases differs from quantum liquids. While the first one leads to Enskog-type of corrections to the kinetic theory, the latter ones are described by quasiparticle concepts of Landau-type theories. A unifying kinetic theory is envisaged by the nonlocal quantum kinetic theory. Nonequilibrium phenomena are the essential processes which occur in nature. Any evolution is built up of involved causal networks which may render a new state of quality in the course of time evolution. The steady state or equilibrium is rather the exception in nature, if not a theoretical abstraction at all.

scholarly journals Spatiotemporal analysis of the runaway distribution function from synchrotron images in an ASDEX Upgrade disruption

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
M. Hoppe ◽  
L. Hesslow ◽  
O. Embreus ◽  
L. Unnerfelt ◽  
G. Papp ◽  
...  
Keyword(s):  
Radial Profile ◽  
Spatiotemporal Analysis ◽  
High Energy ◽  
Synchrotron Emission ◽  
Analytic Model ◽  
Runaway Electrons ◽  
Radial Density ◽  
Radial Density Profile ◽  
Argon Injection ◽  
Seed Population

Synchrotron radiation images from runaway electrons (REs) in an ASDEX Upgrade discharge disrupted by argon injection are analysed using the synchrotron diagnostic tool Soft and coupled fluid-kinetic simulations. We show that the evolution of the runaway distribution is well described by an initial hot-tail seed population, which is accelerated to energies between 25–50 MeV during the current quench, together with an avalanche runaway tail which has an exponentially decreasing energy spectrum. We find that, although the avalanche component carries the vast majority of the current, it is the high-energy seed remnant that dominates synchrotron emission. With insights from the fluid-kinetic simulations, an analytic model for the evolution of the runaway seed component is developed and used to reconstruct the radial density profile of the RE beam. The analysis shows that the observed change of the synchrotron pattern from circular to crescent shape is caused by a rapid redistribution of the radial profile of the runaway density.

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