Showing papers by "Princeton Plasma Physics Laboratory published in 2008"
TL;DR: In this paper, a cascade model is presented, based on the assumptions of local nonlinear energy transfer in Wavenumber space, critical balance between linear propagation and nonlinear interaction times, and the applicability of linear dissipation rates for the nonlinearly turbulent plasma.
Abstract: This paper studies the turbulent cascade of magnetic energy in weakly col- lisional magnetized plasmas. A cascade model is presented, based on the assumptions of local nonlinear energy transfer in wavenumber space, critical balance between linear propagation and nonlinear interaction times, and the applicability of linear dissipation rates for the nonlinearly turbulent plasma. The model follows the nonlinear cascade of energy from the driving scale in the MHD regime, through the transition at the ion Lar- mor radius into the kinetic Alfven wave regime, in which the turbulence is dissipated by kinetic processes. The turbulent fluctuations remain at frequencies below the ion cy- clotron frequency due to the strong anisotropy of the turbulent fluctuations, kk ≪ k⊥ (implied by critical balance). In this limit, the turbulence is optimally described by gy- rokinetics; it is shown that the gyrokinetic approximation is well satisfied for typical slow solar wind parameters. Wave phase velocity measurements are consistent with a kinetic Alfven wave cascade and not the onset of ion cyclotron damping. The conditions under which the gyrokinetic cascade reaches the ion cyclotron frequency are established. Cas- cade model solutions imply that collisionless damping provides a natural explanation for the observed range of spectral indices in the dissipation range of the solar wind. The dis- sipation range spectrum is predicted to be an exponential fall off; the power-law behav- ior apparent in observations may be an artifact of limited instrumental sensitivity. The cascade model is motivated by a programme of gyrokinetic simulations of turbulence and particle heating in the solar wind.
377 citations
TL;DR: The first ab initio, fully electromagnetic, kinetic simulations of magnetized turbulence in a homogeneous, weakly collisional plasma at the scale of the ion Larmor radius (ion gyroscale) support the hypothesis that the frequencies of turbulent fluctuations in the solar wind remain well below the ion cyclotron frequency.
Abstract: This Letter presents the first ab initio, fully electromagnetic, kinetic simulations of magnetized turbulence in a homogeneous, weakly collisional plasma at the scale of the ion Larmor radius (ion gyroscale). Magnetic- and electric-field energy spectra show a break at the ion gyroscale; the spectral slopes are consistent with scaling predictions for critically balanced turbulence of Alfven waves above the ion gyroscale (spectral index -5/3) and of kinetic Alfven waves below the ion gyroscale (spectral indices of -7/3 for magnetic and -1/3 for electric fluctuations). This behavior is also qualitatively consistent with in situ measurements of turbulence in the solar wind. Our findings support the hypothesis that the frequencies of turbulent fluctuations in the solar wind remain well below the ion cyclotron frequency both above and below the ion gyroscale.
354 citations
TL;DR: The handling and safety of GaInSn is described based on the experience gained in the Magneto-Thermofluid Research Laboratory and Princeton Plasma Physics Laboratory, augmented by observations from other researchers in the liquid metal experimental community.
Abstract: GaInSn, a eutectic alloy, has been successfully used in the Magneto-Thermofluid Research Laboratory at the University of California-Los Angeles and at the Princeton Plasma Physics Laboratory for the past six years. This paper describes the handling and safety of GaInSn based on the experience gained in these institutions, augmented by observations from other researchers in the liquid metal experimental community. GaInSn is an alloy with benign properties and shows considerable potential in liquid metal experimental research and cooling applications.
232 citations
TL;DR: A new energetic particle-induced geodesic acoustic mode (EGAM) is shown to exist and the mode frequency and mode structure are determined nonperturbatively by energetic particle kinetic effects.
Abstract: A new energetic particle-induced Geodesic Acoustic Mode (EGAM) is shown to exist. The mode frequency, mode structure, and mode destabilization are determined non-perturbatively by energetic particle kinetic effects. In particular the EGAM frequency is found to be substantially lower than the standard GAM frequency. The radial mode width is determined by the energetic particle drift orbit width and can be fairly large for high energetic particle pressure and large safety factor. These results are consistent with the recent experimental observation of the beam- driven n=0 mode in DIII-D. The new mode is important since it can degrade energetic particle confinement as shown in the DIII-D experiments. The new mode may also affect the thermal plasma confinement via its interaction with plasma micro-turbulence.
179 citations
TL;DR: Ono et al. as discussed by the authors applied lithium coatings to plasma facing components found previously in limited plasmas can occur also in high-power diverted configurations, and the results showed that benefits from the coatings were sometimes, but not always, seen.
Abstract: National Spherical Torus Experiment [which M. Ono et al., Nucl. Fusion 40, 557 (2000)] high-power divertor plasma experiments have shown, for the first time, that benefits from lithium coatings applied to plasma facing components found previously in limited plasmas can occur also in high-power diverted configurations. Lithium coatings were applied with pellets injected into helium discharges, and also with an oven that directed a collimated stream of lithium vapor toward the graphite tiles of the lower center stack and divertor. Lithium oven depositions from a few milligrams to 1g have been applied between discharges. Benefits from the lithium coatings were sometimes, but not always, seen. These benefits sometimes included decreases in plasma density, inductive flux consumption, and edge-localized mode occurrence, and increases in electron temperature, ion temperature, energy confinement, and periods of edge and magnetohydrodynamic quiescence. In addition, reductions in lower divertor D, C, and O luminosi...
165 citations
TL;DR: In this article, a conceptual framework for understanding kinetic plasma turbulence as a generalized form of energy cascade in phase space is presented, emphasizing that conversion of turbulent energy into thermodynamic heat is only achievable in the presence of some (however small) degree of collisionality.
Abstract: This paper describes a conceptual framework for understanding kinetic plasma turbulence as a generalized form of energy cascade in phase space. It is emphasized that conversion of turbulent energy into thermodynamic heat is only achievable in the presence of some (however small) degree of collisionality. The smallness of the collision rate is compensated for by the emergence of a small-scale structure in the velocity space. For gyrokinetic turbulence, a nonlinear perpendicular phase-mixing mechanism is identified and described as a turbulent cascade of entropy fluctuations simultaneously occurring at spatial scales smaller than the ion gyroscale and in velocity space. Scaling relations for the resulting fluctuation spectra are derived. An estimate for the collisional cutoff is provided. The importance of adequately modelling and resolving collisions in gyrokinetic simulations is briefly discussed, as well as the relevance of these results to understanding the dissipation-range turbulence in the solar wind and the electrostatic microturbulence in fusion plasmas.
149 citations
TL;DR: Intense axisymmetric oscillations driven by suprathermal ions injected in the direction counter to the toroidal plasma current are observed in the DIII-D tokamak, confirming a dominant compressional contribution to the pressure perturbation as predicted by kinetic theory.
Abstract: Intense axisymmetric oscillations driven by suprathermal ions injected in the direction counter to the toroidal plasma current are observed in the DIII-D tokamak. The modes appear at nearly half the ideal geodesic acoustic mode frequency, in plasmas with comparable electron and ion temperatures and elevated magnetic safety factor (qmin � 2). Strong bursting and frequency chirping are observed, concomitant with large (10%–15%) drops in the neutron emission. Large electron density fluctuations (~ ne=ne ’ 1:5%) are observed with no detectable electron temperature fluctuations, confirming a dominant compressional contribution to the pressure perturbation as predicted by kinetic theory. The observed mode frequency is consistent with a recent theoretical prediction for the energetic-particle-driven geodesic acoustic mode.
140 citations
TL;DR: The observed magnitude, direction, and radial profile of the offset rotation are consistent with neoclassical theory predictions and result in improvement in the global energy confinement time.
Abstract: We present the first evidence for the existence of a neoclassical toroidal rotation driven in a direction counter to the plasma current by nonaxisymmetric, nonresonant magnetic fields. At high beta and with large injected neutral beam momentum, the nonresonant field torque slows down the plasma toward the neoclassical ``offset'' rotation rate. With small injected neutral beam momentum, the toroidal rotation is accelerated toward the offset rotation, with resulting improvement in the global energy confinement time. The observed magnitude, direction, and radial profile of the offset rotation are consistent with neoclassical theory predictions [A. J. Cole et al., Phys. Rev. Lett. 99, 065001 (2007)].
138 citations
TL;DR: In this article, the toroidal helical Fourier harmonic spectrum of the ITER plasmas was derived from DIII-D ELM suppression experiments, and it was shown that large arrays of coils (e.g. four toroidal rows of nine coils each) on the outboard wall near the plasma (at the radius of the blanket-vacuum vessel interface R ~ 8 m) can meet the known requirements for both low and high-q ITER PLASmas, when coil currents are distributed to concentrate the magnetic perturbation into a
Abstract: Large Type-I edge-localized mode (ELM) heat pulses may limit the life of divertor targets in a burning plasma. Recent experiments show that pitch-resonant nonaxisymmetric magnetic perturbations of the plasma edge of 0.0005 or less of the main magnetic field offer a useful solution, but there is little room in the presently designed ITER for even small perturbation coils. We present proposed coil requirements for ITER ELM suppression, derived primarily from DIII-D ELM suppression experiments. We show by calculated examples that large arrays of coils (e.g. four toroidal rows of nine coils each) on the outboard wall near the plasma (at the radius of the blanket-vacuum vessel interface R ~ 8 m) can meet the known requirements, expressed in terms of the toroidal helical Fourier harmonic spectrum, for both low- and high-q ITER plasmas, when coil currents are distributed to concentrate the magnetic perturbation into a single dominant Fourier spectral peak. Fields from arrays of less than four rows of nine coils (a) penetrate relatively more strongly into the core plasma, and (b) generate more and larger nonresonant spectral peaks. Both features are expected to brake desirable plasma rotation. We found that the Moire effect from approximating sinusoidal perturbations by a limited discrete coil set can be used to control nonfundamental harmonics in large arrays. We show that a judicious choice of current distribution among the coils ameliorates effects of an 80° toroidal gap where no coils are allowed in the ITER midplane.
131 citations
TL;DR: Experimental advanced superconducting tokamak (EAST), the first tokomak with ITER-like fully superconductive poloidal and toroidal coils, successfully completed its engineering commission in March 2006; had its first plasma in September 2006 [B.N. Wan, et al., the authors ], and further generated diverted plasma in January 2007.
87 citations
TL;DR: Magnetic data are used in real time to measure and control the current, shape, and position of the discharge; the thermal energy of the plasma; the confining magnetic field; and the currents in the magnet coils as discussed by the authors.
Abstract: Magnetic diagnostics are essential for the operation and understanding of a magnetic fusion device. Magnetic data are used in real time to measure and control the current, shape, and position of the discharge; the thermal energy of the plasma; the confining magnetic field; and the currents in the magnet coils. Equilibrium reconstructions based on magnetic data yield the magnetic geometry of the plasma, providing the coordinates for interpretation of all other diagnostic measurements. Magnetic measurements also provide input for the analysis and feedback control of magnetohydrodynamic (MHD) instabilities. This review focuses on the inductive loops and Hall effect probes that are used in nearly all present devices. We describe the principles of magnetic diagnostics and discuss issues related to their practical implementation. The interpretation of magnetic measurements for equilibrium reconstruction and for identification of MHD instabilities are summarized. Magnetic diagnostics based on inductive m...
TL;DR: Experimental observations and agreement with numerical results from a linear gyrokinetic stability code support the conjecture that the observed turbulence is driven by the electron-temperature gradient.
Abstract: Measurements with coherent scattering of electromagnetic waves in plasmas of the National Spherical Torus Experiment indicate the existence of turbulent fluctuations in the range of wave numbers ${k}_{\ensuremath{\perp}}{\ensuremath{\rho}}_{e}=0.1--0.4$, corresponding to a turbulence scale length nearly equal to the collisionless skin depth. Experimental observations and agreement with numerical results from a linear gyrokinetic stability code support the conjecture that the observed turbulence is driven by the electron-temperature gradient.
TL;DR: In this article, an 80kW RFEF pilot plant system was used to process cider at flow rates of 1.5 and 1.9 l/min at frequencies of 21, 30, and 41 kHz.
TL;DR: In this article, the variation of magnetic helicity over a span of several days around the times of 11 X-class flares which occurred in seven active regions (NOAA 9672, 10030, 10314, 10486, 10564, 10696, and 10720) using the magnetograms taken by the Michelson Doppler Imager (MDI) on board the SOHO.
Abstract: We have investigated the variation of magnetic helicity over a span of several days around the times of 11 X-class flares which occurred in seven active regions (NOAA 9672, 10030, 10314, 10486, 10564, 10696, and 10720) using the magnetograms taken by the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO). As a major result we found that each of these major flares was preceded by a significant helicity accumulation, (1.8–16) × 1042 Mx2 over a long period (0.5 to a few days). Another finding is that the helicity accumulates at a nearly constant rate, (4.5–48) × 1040 Mx2 hr−1, and then becomes nearly constant before the flares. This led us to distinguish the helicity variation into two phases: a phase of monotonically increasing helicity and the following phase of relatively constant helicity. As expected, the amount of helicity accumulated shows a modest correlation with time-integrated soft X-ray flux during flares. However, the average helicity change rate in the first phase shows even stronger correlation with the time-integrated soft X-ray flux. We discuss the physical implications of this result and the possibility that this characteristic helicity variation pattern can be used as an early warning sign for solar eruptions.
TL;DR: In this article, a comparison between laboratory observations of electron scale dissipation layers near a reconnecting X-line and direct two-dimensional full-particle simulations is made, which suggests that, in addition to the residual collisions, 3D effects play an important role in electron-scale dissipation during fast reconnection.
Abstract: ELECTRON DISSIPATION IN RECONNECTION Detailed comparisons are reported between laboratory observations of electron scale dissipation layers near a reconnecting X-line and direct two-dimensional full-particle simulations. Many experimental features of the electron layers, such as insensitivity to the ion mass, are reproduced by the simulations; the layer thickness, however, is about 3 - 5 times larger than the predictions. Consequently, the leading candidate 2D mechanism based on collisionless electron nongyrotropic pressure is insuffcient to explain the observed reconnection rates. These results suggest that, in addition to the residual collisions, 3D effects play an important role in electron-scale dissipation during fast reconnection.
TL;DR: In this article, a new method for correcting magnetic field errors in the ITER tokamak was developed using the Ideal Perturbed Equilibrium Code (IPEC). And the dominant external magnetic field for driving islands was shown to be localized to the outboard midplane for three ITER equilibria that represent the projected range of operational scenarios.
Abstract: A new method for correcting magnetic field errors in the ITER tokamak is developed using the Ideal Perturbed Equilibrium Code. The dominant external magnetic field for driving islands is shown to be localized to the outboard midplane for three ITER equilibria that represent the projected range of operational scenarios. The coupling matrices between the poloidal harmonics of the external magnetic perturbations and the resonant fields on the rational surfaces that drive islands are combined for different equilibria and used to determine an ordered list of the dominant errors in the external magnetic field. It is found that efficient and robust error field correction is possible with a fixed setting of the correction currents relative to the currents in the main coils across the range of ITER operating scenarios that was considered.
University of California, San Diego1, Kanazawa University2, National Autonomous University of Mexico3, Lawrence Livermore National Laboratory4, General Atomics5, Princeton Plasma Physics Laboratory6, Massachusetts Institute of Technology7, Nagoya University8, Kyushu University9, Japan Atomic Energy Agency10, Princeton University11
TL;DR: In this paper, the authors review recent progress in the understanding of different experimental and theoretical aspects of the physics of dust dynamics and transport in fusion plasmas and discuss the remaining issues.
Abstract: It has been known for a long time that microscopic dust appears in plasmas in fusion devices. Recently it was shown that dust can be responsible for the termination of long- discharges. Also, in ITER-scale experiments dust can pose safety problems related to its chemical activity, tritium retention and radioactive content. In particular, the presence of dust in the vacuum chamber of ITER is one of the main concerns of the ITER licensing process. Here we review recent progress in the understanding of different experimental and theoretical aspects of the physics of dust dynamics and transport in fusion plasmas and discuss the remaining issues.
TL;DR: Spectroscopy of radiation emitted by impurities and hydrogen isotopes plays an important role in the study of magnetically confined fusion plasmas, both in determining the effects of impurities on the magnetic field and hydrogen atoms.
Abstract: Spectroscopy of radiation emitted by impurities and hydrogen isotopes plays an important role in the study of magnetically confined fusion plasmas, both in determining the effects of impurities on ...
TL;DR: Microwave-based diagnostics have found broad application in magnetic fusion plasma diagnostics and are expected to be widely employed in future burning plasma experiments (BPXs) as mentioned in this paper.
Abstract: Microwave-based diagnostics have found broad application in magnetic fusion plasma diagnostics and are expected to be widely employed in future burning plasma experiments (BPXs). Most of these tech...
TL;DR: Improvements have been made in both stochastic and deterministic radiation transport methodologies and their new capabilities will be compared briefly, with particular attention to how these new capabilities provide new insights for engineering design of ITER components.
TL;DR: Steady state solutions for anisotropic heat transport in a chaotic magnetic field are determined numerically and compared to a set of "ghost surfaces"-surfaces constructed via an action-gradient flow between the minimax and minimizing periodic orbits in remarkable agreement with the temperature contours.
Abstract: Steady state solutions for anisotropic heat transport in a chaotic magnetic field are determined numerically and compared to a set of "ghost-surfaces", surfaces constructed via an action-gradient flow between the minimax and minimizing periodic orbits. The ghost-surfaces are in remarkable agreement with the temperature contours.
TL;DR: The first identification of the electron-diffusion region, where demagnetized electrons are accelerated to super-Alfvénic speed, in a reconnecting laboratory plasma is reported.
Abstract: We report the first identification of the electron diffusion region, where demagnetized electrons are accelerated to super-Alfvenic speed, in a reconnecting laboratory plasma. The electron diffusion region is determined from measurements of the out-of-plane quadrupole magnetic field in the neutral sheet in the Magnetic Reconnection Experiment. The width of the electron diffusion region scales with the electron skin depth (~ 5.5-7.5c=ωpi) and the peak electron outflow velocity scales with the electron Alfven velocity (~ 0.12 - 0.16VeA), independent of ion mass.
TL;DR: It is shown that using a simple, model insensitive ansatz of conservation of total angular momentum, a TEP pinch of angular momentum can be obtained and that the nondiffusive TEP flux is inward, which may explain the peakedness of the rotation profiles observed in certain experiments.
Abstract: A physical model of turbulent equipartition (TEP) of plasma angular momentum is developed. We show that using a simple, model insensitive ansatz of conservation of total angular momentum, a TEP pinch of angular momentum can be obtained. We note that this term corresponds to a part of the pinch velocity previously calculated using quasilinear gyrokinetic theory. We observe that the nondiffusive TEP flux is inward, and therefore may explain the peakedness of the rotation profiles observed in certain experiments. Similar expressions for linear toroidal momentum and flow are computed and it is noted that there is an additional effect due the radial profile of moment of inertia density.
TL;DR: This paper documents the public release PR08 of the International Tokamak Physics Activity (ITPA) profile database, which should be of particular interest to the magnetic confinement fusion community.
Abstract: This paper documents the public release PR08 of the International Tokamak Physics Activity (ITPA) profile database, which should be of particular interest to the magnetic confinement fusion community. Data from a wide variety of interesting discharges from many of the world's leading tokamak experiments are now made available in PR08, which also includes predictive simulations of an initial set of operating scenarios for ITER. In this paper we describe the discharges that have been included and the tools that are available to the reader who is interested in accessing and working with the data. Most discharge descriptions refer to more detailed previous publications. In addition, we review physics analyses that have already made use of the profile database discharges. Public access to PR08 data is unconditional, but this paper should be cited by any publication that makes use of PR08 data.
TL;DR: A collective scattering system has been installed on the National Spherical Torus Experiment (NSTX) to measure electron gyroscale fluctuations in NSTX plasmas, and initial measurements indicate rich turbulent dynamics on the electron Gyroscale.
Abstract: A collective scattering system has been installed on the National Spherical Torus Experiment (NSTX) to measure electron gyroscale fluctuations in NSTX plasmas Up to five distinct wavenumbers are measured simultaneously, and the large toroidal curvature of NSTX plasmas provides enhanced spatial localization Steerable optics can position the scattering volume throughout the plasma from the magnetic axis to the outboard edge Initial measurements indicate rich turbulent dynamics on the electron gyroscale The system will be a valuable tool for investigating the connection between electron temperature gradient turbulence and electron thermal transport in NSTX plasmas
TL;DR: In this article, fast-ion Dα (FIDA) spectroscopy was applied to the DIII-D tokamak to study the toroidicity-induced and reversed-shear Alfven eigenmodes.
Abstract: Neutral beam injection into a plasma with negative central shear produces a rich spectrum of toroidicity-induced and reversed-shear Alfven eigenmodes in the DIII-D tokamak. The application of fast-ion Dα (FIDA) spectroscopy shows that the central fast-ion profile is flattened in the inner half of the discharge. Neutron and equilibrium measurements corroborate the FIDA data. The temporal evolution of the current profile is also strongly modified. Studies in similar discharges show that flattening of the profile correlates with the mode amplitude and that both types of Alfven modes correlate with fast-ion transport. Calculations by the ORBIT code do not explain the observed fast-ion transport for the measured mode amplitudes, however. Possible explanations for the discrepancy are considered.
TL;DR: In this article, a lower hybrid (LH) current drive was simulated using the combined ray tracing/three-dimensional (r,v⊥,v∥) Fokker-Planck code GENRAY-CQL3D.
Abstract: Lower hybrid (LH) current drive experiments have been carried out on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] using a radio-frequency system at 4.6GHz. Up to 900kW of LH power has been coupled and driven LH currents have been inferred from magnetic measurements by extrapolating to zero loop voltage, yielding an efficiency of neILHR0∕PLH≈2.5±0.2×1019(A∕W∕m2). We have simulated the LH current drive in these discharges using the combined ray tracing/three-dimensional (r,v⊥,v∥) Fokker–Planck code GENRAY-CQL3D (R. W. Harvey and M. McCoy, in Proceedings of the IAEA Technical Committee Meeting on Simulation and Modeling of Thermonuclear Plasmas, Montreal, Canada, 1992) and found similar current drive efficiencies. The simulated profiles of current density from CQL3D, including both ohmic plus LH drive have been found to be in good agreement with the measured current density from a motional Stark effect diagnostic. Measurements of nonthermal x-ray emission confirm the pres...
TL;DR: A scintillator based energetic ion loss detector has been built and installed on the National Spherical Torus Experiment (NSTX) to measure the loss of neutral beam ions.
Abstract: A scintillator based energetic ion loss detector has been built and installed on the National Spherical Torus Experiment (NSTX) to measure the loss of neutral beam ions. The detector is able to resolve the pitch angle and gyroradius of the lost energetic ions. It has a wide acceptance range in pitch angle and energy, and is able to resolve the full, one-half, and one-third energy components of the 80 keV D neutral beams up to the maximum toroidal magnetic field of NSTX. Multiple Faraday cups have been embedded behind the scintillator to allow easy absolute calibration of the diagnostic and to measure the energetic ion loss to several ranges of pitch angle with good time resolution. Several small, vacuum compatible lamps allow simple calibration of the scintillator position within the field of view of the diagnostic's video camera.
TL;DR: Experiments have been conducted at the National Sperical Torus Experiment (NSTX) to study both steady state and perturbative momentum transport, where the low aspect ratio of NSTX results in rapid plasma rotation with ExB shearing rates high enough to suppress low-k turbulence.
Abstract: Experiments have been conducted at the National Sperical Torus Experiment (NSTX) to study both steady state and perturbative momentum transport. These studies are unique in their parameter space under investigation, where the low aspect ratio of NSTX results in rapid plasma rotation with $E\ifmmode\times\else\texttimes\fi{}B$ shearing rates high enough to suppress low-$k$ turbulence. In some cases, the ratio of momentum to energy confinement time is found to exceed five. Momentum pinch velocities of order $10--40\text{ }\text{ }\mathrm{m}/\mathrm{s}$ are inferred from the measured angular momentum flux evolution after nonresonant magnetic perturbations are applied to brake the plasma.
TL;DR: In this paper, the authors show that the degree of RSAE stabilization, fast ion density and the volume averaged neutron production are highly dependent on ECH deposition location relative to qmin.
Abstract: Reversed shear Alfveigenmode (RSAE) activity in DIII-D is stabilized by electron cyclotron heating (ECH) applied near the minimum of the magnetic safety factor (qmin) in neutral beam heated discharges with reversed-magnetic shear. The degree of RSAE stabilization, fast ion density and the volume averaged neutron production (Sn) are highly dependent on ECH deposition location relative to qmin. While discharges with ECH stabilization of RSAEs havehigher Sn andmorepeakedfastionprofilesthandischargeswithsignificant RSAEactivity,neutronproductionremainsstronglyreduced(upto60%relative toTRANSPpredictionsassumingclassicalfastiontransport)evenwhenRSAEs are stabilized. (Some figures in this article are in colour only in the electronic version)