Simulation of runaway electron generation during plasma shutdown by impurity injection in ITER

Fehér, Tamás; Smith, H. M.; Fülöp, Tünde; Gál, K.

doi:10.1088/0741-3335/53/3/035014

Cited by 63 publications

(101 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Studies were made in ref. [12] to test the influence of this assumption on the GO simulation results. Radiation has the strongest cooling effect on the electrons.…”

Section: Numerical Modelmentioning

confidence: 99%

The effect of ITER-like wall on runaway electron generation in JET

Papp¹,

Fülöp²,

Fehér³

et al. 2013

Nucl. Fusion

View full text Add to dashboard Cite

Abstract.This paper investigates the effect of the ITER-like wall (ILW) on runaway electron (RE) generation through a comparative study of similar slow argon injection JET disruptions, performed with different wall materials. In the carbon wall case, a runaway electron plateau is observed, while in the ITER-like wall case, the current quench is slower and the runaway current is negligibly small. The aim of the paper is to shed light on the reason for these differences by detailed numerical modelling to study which factors affected the RE formation. The post-disruption current profile is calculated by a one-dimensional model of electric field, temperature and runaway current taking into account the impurity injection. Scans of various impurity contents are performed and agreement with the experimental scenarios is obtained for reasonable argon-and wall impurity contents. Our modelling shows that the reason for the changed RE dynamics is a complex, combined effect of the differences in plasma parameter profiles, the radiation characteristics of beryllium and carbon, and the difference of the injected argon amount. These together lead to a significantly higher Dreicer generation rate in the carbon wall case, which is less prone to be suppressed by RE loss mechanisms. The results indicate that the differences are greatly reduced above ∼50% argon content,The effect of ITER-like wall on runaway electron generation in JET 2 suggesting that significant RE current is expected in future massive gas injection experiments on both JET and ITER.

show abstract

“…Studies were made in ref. [12] to test the influence of this assumption on the GO simulation results. Radiation has the strongest cooling effect on the electrons.…”

Section: Numerical Modelmentioning

confidence: 99%

The effect of ITER-like wall on runaway electron generation in JET

Papp¹,

Fülöp²,

Fehér³

et al. 2013

Nucl. Fusion

View full text Add to dashboard Cite

show abstract

“…During the rapid plasma cooling, being relevant to rapid shutdown scenarios like the massive gas injection, the incomplete thermalization of the electron distribution function yields hot-tail seeds [10][11][12][13][14][15][16][17][18]. To simulate the hot-tail generation during TQ, an initial-value Fokker-Planck routine is coupled self-consistently to the 0D TQ simulations of the INDEX code.…”

Section: Hot-tail Electron Production During Massive Ar Injectionmentioning

confidence: 99%

“…Thirdly, primary (seed) runaways required for triggering the avalanche growth are sensitive to dynamic changes of the plasma parameters during TQ. At the high density conditions, hot-tail seeds [10][11][12][13][14][15][16][17][18] can be a dominant mechanism when the Dreicer seed electrons are suppressed. For the development of rapid shutdown scenarios using massive noble-gas injection, the production of hot-tail seed electrons during rapid TQ must be taken into account.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Avalanche Runaway Generation after Disruptions with Low-<i>Z </i>and Noble Gas Species

Matsuyama

Yagi

2017

Plasma and Fusion Research

View full text Add to dashboard Cite

The effects of impurities on runaway electron generation are studied using a zero-dimensional disruption simulation code. For describing collisions between fast electrons and partially stripped ions, a charge-resolved expression of the Coulomb logarithm is employed. Numerical analysis of the avalanche growth rate using the adjoint Fokker-Planck method is compared with two existing semi-analytic models, showing (i) the convergence of the growth rate to strong electric field limit of the Rosenbluth-Putvinski (R-P) model and (ii) the cancellation of the effect of second-order collisional diffusion for intermediate electric fields. Using the developed current quench (CQ) simulations, the parametric study is performed with the aid of the power balance analysis, which characterizes the onset of strong avalanche amplification in the presence of low-Z and noble gas species. Thermal quench (TQ) simulations are also developed for self-consistent evaluation of hot-tail seed electrons. The deposition timescale of impurity neutrals is shown to have significant impacts on hot-tail seeds, depending nonmonotonically on the pre-TQ temperature and the injected impurity density.

show abstract

“…Charged particle is confined in a small area around the magnetic field line in high-intensity magnetic field, and the center of spiral orbit can only move along but cannot across the magnetic field line. A large number of electrons do spiral motion around the magnetic field line of force adopt the radial electric field and the axial magnetic field, and electrons drift along the magnetic field lines in the magnetic field [7][8][9][10][11][12][13]. The total energy remains constant, and the particle's vertical velocity becomes larger and parallel velocity reduces in the strong magnetic field; the particle's vertical velocity reduces and parallel velocity becomes larger in the weak magnetic field [14].…”

Section: Introductionmentioning

confidence: 99%