Deuterium beam acceleration with 3rd harmonic ion cyclotron resonance heating in Joint European Torus: Sawtooth stabilization and Alfvén eigenmodes

Abstract

Experiments on accelerating NBI-produced deuterium (D) beam ions from their injection energy of $ 110 keV up to the MeV energy range with 3rd harmonic ion cyclotron resonance heating were performed on the Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)]. A renewed set of nuclear diagnostics was used for analysing fast D ions during sawtooth stabilization, monster sawtooth crashes, and during excitation of Alfvén eigenmodes (AEs) residing inside the q ¼ 1 radius. The measurements and modeling of the fast ions with the nonlinear HAGIS code [S. D. Pinches et al., Comput. Phys. Commun. 111, 133 (1998)] show that monster sawtooth crashes are strongly facilitated by the AE-induced re-distribution of the fast D ions from inside the q ¼ 1 radius to the plasma edge. [http://dx.

Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus

“…4 More recently, they have contributed to fundamental studies on the physics of suprathermal ions in thermonuclear plasmas, mostly by detailed measurements of the distribution function of the energetic ions [5][6][7] and their effects on the plasma stability. 8,9 Advanced neutron spectroscopy measurements are nowadays performed along a single, collimated line of sight by means of dedicated, non-compact detectors, based on the time of flight technique [10][11][12] for deuterium-deuterium (dd) fusion neutrons and on proton recoil for deuterium-tritium (dt). 13 These instruments typically show a good energy resolution (between 5% and 7%) and a wide dynamic range sensitivity (up to 5 orders of magnitude in the case of proton recoil) that allows detecting even the very small components (at the 10 −3 -10 −5 level) induced by fast ion nuclear elastic scattering in the plasma.…”

Study of Interaction between Fast Ions and MHD Instabilities by Fusion Product Measurements in Joint European Torus

“…Together with the neutron spectrometry available for D-D reactions, much better coverage of the fast ion redistribution by the tornado modes was experimentally obtained. These experiments provide a very good foundation for sawtooth and tornado modelling [20].…”

“…The change in the equilibrium profiles, as a result of the sawtooth crash, most notably for the safety factor, q, then violates the existence criterion for the tornado modes which accounts for their abrupt disappearance. The modelling of D-ion redistribution [20] in the presence of tornado modes has been carried out with HAGIS [21] using HELENA [22] equilibrium and TAE modes calculated using the CASTOR code [23].…”

Recent progress in fast-ion diagnostics for magnetically confined plasmas

“…The harsh environment in ITER-a nuclear machine-places a number of constraints on standard fast-ion loss detection techniques unprecedented on present tokamaks with easier access and more tolerable conditions. On the basis of the physics requirements and integration capabilities, the Port Plugs and Diagnostics Integration Division at ITER Organization has started to undertake a conceptual study of a reciprocating FILD system for ITER (García-Muñoz et al 2016).…”

“…ASCOT simulations of -particle heat load in ITER on a 3D first wall due to an externally applied n = 4 RMP. The location of the FILD head is indicated with a white box.Figure takenfromGarcía-Muñoz et al (2016) …”