Estimation of synchrotron radiation and limiting energy of high-energy runaway electrons in tokamak stochastic magnetic fields

2006 ◽  
Vol 13 (1) ◽  
pp. 012508 ◽  
Author(s):  
J. R. Martín-Solís ◽  
R. Sánchez
Keyword(s):  
Synchrotron Radiation ◽  
Magnetic Fields ◽  
High Energy ◽  
Runaway Electrons ◽  
Stochastic Magnetic Fields

scholarly journals High energy particle transport in stochastic magnetic fields in the solar corona

2006 ◽  
Vol 462 (3) ◽  
pp. 1113-1120 ◽  
Author(s):  
M. Gkioulidou ◽  
G. Zimbardo ◽  
P. Pommois ◽  
P. Veltri ◽  
L. Vlahos
Keyword(s):  
Magnetic Fields ◽  
Solar Corona ◽  
Particle Transport ◽  
High Energy ◽  
High Energy Particle ◽  
Energy Particle ◽  
Stochastic Magnetic Fields

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.

scholarly journals Effects of magnetic perturbations and radiation on the runaway avalanche

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
P. Svensson ◽  
O. Embreus ◽  
S. L. Newton ◽  
K. Särkimäki ◽  
O. Vallhagen ◽  
...  
Keyword(s):  
Growth Rate ◽  
Runaway Electrons ◽  
Plasma Parameters ◽  
Perturbative Approach ◽  
Efficient Simulation ◽  
Strong Current ◽  
Magnetic Perturbations ◽  
Space Dynamics ◽  
Stochastic Magnetic Fields ◽  
Mitigation Methods

The electron runaway phenomenon in plasmas depends sensitively on the momentum- space dynamics. However, efficient simulation of the global evolution of systems involving runaway electrons typically requires a reduced fluid description. This is needed, for example, in the design of essential runaway mitigation methods for tokamaks. In this paper, we present a method to include the effect of momentum-dependent spatial transport in the runaway avalanche growth rate. We quantify the reduction of the growth rate in the presence of electron diffusion in stochastic magnetic fields and show that the spatial transport can raise the effective critical electric field. Using a perturbative approach, we derive a set of equations that allows treatment of the effect of spatial transport on runaway dynamics in the presence of radial variation in plasma parameters. This is then used to demonstrate the effect of spatial transport in current quench simulations for ITER-like plasmas with massive material injection. We find that in scenarios with sufficiently slow current quench, owing to moderate impurity and deuterium injection, the presence of magnetic perturbations reduces the final runaway current considerably. Perturbations localised at the edge are not effective in suppressing the runaways, unless the runaway generation is off-axis, in which case they may lead to formation of strong current sheets at the interface of the confined and perturbed regions.

ENERGY ORDERING EFFECTS IN THE ARRIVAL DIRECTIONS OF ULTRA-HIGH ENERGY COSMIC RAYS MEASURED BY THE PIERRE AUGER OBSERVATORY

2011 ◽  
Vol 20 (supp02) ◽  
pp. 50-56
Author(s):  
◽  
PETER SCHIFFER
Keyword(s):  
Cosmic Rays ◽  
Magnetic Fields ◽  
Charged Particles ◽  
High Energy ◽  
Pierre Auger Observatory ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
Ordering Effects ◽  
Arrival Directions

The Pierre Auger Observatory is the world's largest experiment for the measurement of ultra-high energy cosmic rays (UHECRs). These UHECRs are assumed to be to be charged particles, and thus are deflected in cosmic magnetic fields. Recent results of the Pierre Auger Observatory addressing the complex of energy ordering of the UHECRs arrival directions are reviewed in this contribution. So far no significant energy ordering has been observed.

X‐ray determination of the Debye temperature at high pressure using high‐energy synchrotron radiation

1990 ◽  
Vol 68 (6) ◽  
pp. 2719-2722 ◽  
Author(s):  
A. Matsumuro ◽  
M. Kobayashi ◽  
T. Kikegawa ◽  
M. Senoo
Keyword(s):  
High Pressure ◽  
Synchrotron Radiation ◽  
Debye Temperature ◽  
High Energy ◽  
X Ray

3-Dimensional Characterization of Polycrystalline Bulk Materials Using High-Energy Synchrotron Radiation

2007 ◽  
Vol 539-543 ◽  
pp. 2353-2358 ◽  
Author(s):  
Ulrich Lienert ◽  
Jonathan Almer ◽  
Bo Jakobsen ◽  
Wolfgang Pantleon ◽  
Henning Friis Poulsen ◽  
...  
Keyword(s):  
High Resolution ◽  
Synchrotron Radiation ◽  
High Energy ◽  
Mapping Technique ◽  
X Ray Diffraction ◽  
Bulk Materials ◽  
Reciprocal Space Mapping ◽  
3 Dimensional ◽  
Individual Grains

The implementation of 3-Dimensional X-Ray Diffraction (3DXRD) Microscopy at the Advanced Photon Source is described. The technique enables the non-destructive structural characterization of polycrystalline bulk materials and is therefore suitable for in situ studies during thermo-mechanical processing. High energy synchrotron radiation and area detectors are employed. First, a forward modeling approach for the reconstruction of grain boundaries from high resolution diffraction images is described. Second, a high resolution reciprocal space mapping technique of individual grains is presented.

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