On the confinement of passing alpha particles in a tokamak-reactor with resonant magnetic field perturbations shielded by plasma currents

Heyn, Martin; Ivanov, Ivan; Kasilov, Sergei; Kernbichler, Winfried; Loarte, A.; Nemov, V. V.; Runov, A.

doi:10.1088/0029-5515/52/5/054010

Cited by 6 publications

(8 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This work focuses on the low toroidal mode number ( = − n 2 3) helical magnetic perturbations typically used for such things as edge-localized mode (ELM) control. Similar coils have been predicted to cause 5% or more loss of neutral beam ions in ITER plasmas [5][6][7][8][9][10], making the accurate and validated modeling of this interaction a priority. Of course, understanding how well fast ions are confined and where they go if lost due to externally applied 3D fields is a key part of not only predicting the performance and ensuring safe operation of future devices, but key for understanding, interpreting, and optimizing experiments on current devices.…”

Section: Introductionmentioning

confidence: 93%

Fast ion transport during applied 3D magnetic perturbations on DIII-D

et al. 2015

View full text Add to dashboard Cite

Measurements show fast ion losses correlated with applied three-dimensional (3D) fields in a variety of plasmas ranging from L-mode to resonant magnetic perturbation (RMP) edge localized mode (ELM) suppressed H-mode discharges. In DIII-D L-mode discharges with a slowly rotating = n 2 magnetic perturbation, scintillator detector loss signals synchronized with the applied fields are observed to decay within one poloidal transit time after beam turnoff indicating they arise predominantly from prompt loss orbits. Full orbit following using M3D-C1 calculations of the perturbed fields and kinetic profiles reproduce many features of the measured losses and points to the importance of the applied 3D field phase with respect to the beam injection location in determining the overall impact on prompt beam ion loss. Modeling of these results includes a self-consistent calculation of the 3D perturbed beam ion birth profiles and scrape-off-layer ionization, a factor found to be essential to reproducing the experimental measurements. Extension of the simulations to full slowing down timescales, including fueling and the effects of drag and pitch angle scattering, show the applied = n 3 RMPs in ELM suppressed H-mode plasmas can induce a significant loss of energetic particles from the core. With the applied = n 3 fields, up to 8.4% of the injected beam power is predicted to be lost, compared to 2.7% with axisymmetric fields only. These fast ions, originating from minor radii ρ > 0.7, are predicted to be primarily passing particles lost to the divertor region, consistent with wide field-of-view infrared periscope measurements of wall heating in = n 3 RMP ELM suppressed plasmas. Edge fast ion α D (FIDA) measurements also confirm a large change in edge fast ion profile due to the = n 3 fields, where the effect was isolated by using short 50 ms RMP-off periods during which ELM suppression was maintained yet the fast ion profile was allowed to recover. The role of resonances between fast ion drift motion and the applied 3D fields in the context of selectively targeting regions of fast ion phase space is also discussed.

show abstract

Section: Introductionmentioning

confidence: 93%

Fast ion transport during applied 3D magnetic perturbations on DIII-D

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The quasilinear transport coefficients (49) are determined by the RMP electromagnetic field in the vicinity of the resonant surface. The estimate of this field for real tokamak geometry is obtained using the method similar to the one used in [11,28]. Presenting the total tokamak field as a sum of the axisymmetric equilibrium field and the perturbation field, B = B 0 + B 1 , these fields are expressed through vector potentials in symmetry flux coordinates (ψ tor , ϑ, ϕ) as follows:…”

Section: Relation To Real Geometrymentioning

confidence: 99%

“…(It should be noted that these form factors do not tend to a constant value at the inner flux surfaces outside the resonant layer because B r(plas) m (r) still satisfies there the ideal MHD equation of [29], see [6].) This method has been used in [11,28] and is used here for estimation of the shielding effect on the perturbed magnetic field topology. Conversely, the transport coefficients (49) computed for the separate perturbation field modes m for the straight cylinder model are multiplied upon the summation with spectral weights given by…”

Section: Relation To Real Geometrymentioning

confidence: 99%

Quasilinear modelling of RMP interaction with a tokamak plasma: application to ASDEX Upgrade ELM mitigation experiments

et al. 2014

View full text Add to dashboard Cite

First experiments on edge-localized mode (ELM) mitigation with the help of ITER-like coils on ASDEX Upgrade are analysed using linear and quasilinear kinetic models to describe the interaction of resonant magnetic field perturbations (RMP) with the plasma. The gyrokinetic derivation of RMP-driven transport coefficients is given in detail. The role of fluid resonances is studied, in particular the role of the resonance associated with the equilibrium electric field reversal point Er = 0. Like the electron fluid resonance associated with the zero of the total perpendicular electron fluid velocity, the Er = 0 resonance may lead to enhanced transport due to the reduction of RMP shielding in the pedestal region where the RMP field can even be amplified by this resonance. The conditions on the RMP coil spectrum resulting from the analysis are discussed.

show abstract

“…This is of special importance for future burning plasmas with a large content of MeV-ions with relatively long slowing-down times. Numerical simulations of fast-ion losses induced by ELM mitigation coils in ITER [5][6][7][8][9] have shown that, under certain conditions, up to 20% of the neutral beam injection (NBI) power can be lost due to the 3D fields created by the ELM mitigation coils. An experimentally validated model for the plasma response is, however, needed to improve our abilities to make realistic predictions for ITER as the plasma can shield or even amplify some components of the externally applied MPs leading to a complex 3D background equilibrium.…”

Section: Introductionmentioning

confidence: 99%