Simulation of runaway electrons, transport affected by J-TEXT resonant magnetic perturbation

Jiang, Zhonghe; Wang, X.H.; Chen, Z.Y.; Huang, Dan; Sun, X.F.; Xu, Tao; Zhuang, G.

doi:10.1088/0029-5515/56/9/092012

Cited by 14 publications

(10 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Note that the microseconds time scale of fast RE loss in this DIII-D experiment, identified as largely drift orbit loss due to large perturbation amplitude, is different from a previous modeling for DIII-D [17], where more than one order of magnitude smaller 3D perturbation field is in presence, and consequently the RE confinement time (∼100 µs or longer) is much longer than the prompt loss time shown in this study. Significant RE mitigation, observed in J-TEXT RMP experiments, has been explained by the drift loss [20], similar to this study.…”

Section: Conclusion and Discussionsupporting

confidence: 90%

“…The JOREK modeling [18] finds that REs, initialized before the TQ, can partially survive the magnetic field stochasticity generated during the TQ, and the survival rate depends on the electron energy range. 3D RMPs, without [19,21] or with [20] inclusion of the plasma response, were also found to modify the RE confinement in small-size tokamaks [19,20] as well as in ITER [21]. The effect of RMP on RE deconfinement is generally expected to be weaker in ITER than that in small size tokamaks such as COMPASS, where large perturbation field, of order δB/B ∼ 10 −2 , was found to induce clear RE loss in recent experiments [22] .…”

Section: Introductionmentioning

confidence: 92%

“…In terms of toroidal modeling, three-dimensional (3D) magnetic field perturbations, either due to magneto-hydrodynamic (MHD) instabilities [17,18] or due to applied resonant magnetic perturbations (RMPs) [19,20], have been found to play certain role in runaway current mitigation. For instance, NIMROD modeling [17] has shown an important dependence of the RE confinement on machine size (C-mod versus DIII-D versus ITER), in the presence of non-linear MHD modes in post thermal quench (TQ) plasmas.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D

et al. 2019

View full text Add to dashboard Cite

A drift orbit model for relativistic test electrons has been incorporated into the MARS-F code (Liu et al 2000 Phys. Plasmas 7 3681), in order to study the runaway electron (RE) behavior in the presence of magneto-hydrodynamic perturbations computed by MARS-F. By implementing the model directly into the MARS-F curve-linear magnetic coordinates, maximal accuracy in representing the full field perturbation is preserved. The updated code is utilized to study the high current RE beam loss in a post-disruption DIII-D plasma, revealing that a fast growing, n = 1 (n is the toroidal mode number) resistive kink instability, at ∼100 Gauss level, can induce significant fraction of RE loss, largely by perturbing drift orbits of REs. A ∼1000 Gauss perturbation fully terminates the RE beam, as found in both experiment and modeling. The 3D field induced loss increases with the perturbation amplitude but decreases with the particle energy. The loss fraction is generally not sensitive to the initial particle pitch angle. The particle velocity change, due to electric field acceleration/deceleration, small pitch angle scattering, synchrotron radiation and Bremsstrahlung, further perturbs the RE trajectory but plays a minor role in prompt RE loss within microseconds time scale. Therefore, the dominant dependencies are simply the RE energy and instability strength. For comparison, a resonant magnetic perturbation field, generated by 4 kAt n = 3 even parity I-coil currents in DIII-D and with the plasma response field included, is found to induce almost no loss for the same RE beam.

show abstract

Section: Conclusion and Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Based on Hamiltonian guiding center equations for runaway electrons, the effect of resonant magnetic perturbation (RMP) on the confinement of runaway electrons is simulated by calculating the orbit losses for different runaway initial energies and different runaway initial locations based on the J-TEXT plasma equilibrium [42]. The result indicates that the loss rate of runaway electrons is sensitive to the radial position of electrons as shown in figure 15.…”

Section: Observations Of Behavior Of Runaway Current Due To Rmpsmentioning

confidence: 99%

Progress of recent experimental research on the J-TEXT tokamak

et al. 2017

View full text Add to dashboard Cite

The progress of experimental research over the last two years on the J-TEXT tokamak is reviewed and reported in this paper, including: investigations of resonant magnetic perturbations (RMPs) on the J-TEXT operation region show that moderate amplitude of applied RMPs either increases the density limit from less than 0.7nG to 0.85nG (nG is the Greenwald density, ) or lowers edge safety factor qa from 2.15 to nearly 2.0; observations of influence of RMPs with a large m/n = 3/1 dominant component (where m and n are the toroidal and poloidal mode numbers respectively) on electron density indicate electron density first increases (decreases) inside (around/outside) of the 3/1 rational surface, and it is increased globally later together with enhanced edge recycling; investigations of the effect of RMPs on the behavior of runaway electrons/current show that application of RMPs with m/n = 2/1 dominant component during disruptions can reduce runaway production. Furthermore, its application before the disruption can reduce both the amplitude and the length of runaway current; experimental results in the high-density disruption plasmas confirm that local current shrinkage during a multifaceted asymmetric radiation from the edge can directly terminate the discharge; measurements by a multi-channel Doppler reflectometer show that the quasi-coherent modes in the electron diamagnetic direction occur in the J-TEXT ohmic confinement regime in a large plasma region (r/a ~ 0.3–0.8) with frequency of 30–140 kHz.

show abstract

“…Past studies have demonstrated the feasibility of RE deconfinement via the application of 3D fields, both with regards to ideal tokamak theory [7,8], experimental demonstration [9][10][11], and predictions for ITER operation [12]. These nonaxisymmetric fields, whether generated in external coils or through intrinsic MHD dynamics of the plasma itself, cause some fraction of the runaway population to undergo drift orbit motion in the radial direction which eventually results in loss to the plasma limiter surface.…”

Section: Introductionmentioning

confidence: 99%

Passive deconfinement of runaway electrons using an in-vessel helical coil

et al. 2021

View full text Add to dashboard Cite

A helical coil designed to passively generate non-axisymmetric fields during a plasma disruption is shown (via electromagnetic analysis, linear MHD modeling, and relativistic drift orbit tracing) to be effective at deconfining runaway electrons (REs) on a time scale significantly faster than the plasma current quench. Magnetic equilibria from DIII-D RE-producing scenarios are used to calculate the toroidal electric field generated during the current quench phase of a disruption, which in turn drives current in the proposed n = 1 in-vessel helical coil, without the need for any external power supplies or disruption detection or prediction techniques. Simulations of the plasma evolution using the TokSys GS Evolve code predict the inductive coupling of coil currents up to 12% of the pre-disruption plasma current into the helical coil. The coil geometry is parametrically varied to maximize both the non-resonant and resonant components of the 3D magnetic perturbation, resulting in δB/B ≈ 10 −2 and a vacuum island overlap width of up to 0.7ψ N . The REORBIT module of the MARS-F code is used to model the full non-axisymmetric magnetic field and trace RE drift orbits to determine the effect on RE deconfinement, with up to 70% of the RE orbits lost after 0.2 ms. A two-stage evolution of the RE orbit loss fraction is observed to be caused by resonant trapping between multiple magnetic island chains. Finally, electromagnetic and thermal stresses on the coil are calculated to be within operational limits for installation in DIII-D, and scale favorably to a reactor-size device. These findings motivate future experimental study of the helical coil concept in DIII-D or other tokamaks.

show abstract

Simulation of runaway electrons, transport affected by J-TEXT resonant magnetic perturbation

Cited by 14 publications

References 28 publications

MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D

MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D

Progress of recent experimental research on the J-TEXT tokamak

Passive deconfinement of runaway electrons using an in-vessel helical coil

Contact Info

Product

Resources

About