Globus-M plasma physics research for fusion application and compact neutron source development

Abstract

During the past decade, plasma physics research promoting the physics base of ITER and developing novel concepts such as a compact fusion neutron source has been conducted on the Globus-M spherical tokamak (ST) (R = 36 cm, a = 24 cm, I p ⩽ 250 kA, B T ⩽ 0.4 T). Tokamak reconstruction is imminent. The upgraded tokamak Globus-M2 will have the same vacuum chamber and an enhanced magnetic system to provide B T = 1 T and I p = 500 kA. In this paper we outline the most important research directions and the main results obtained on Globus-M and make some predictions about the possibilities and parameters of Globus-M2.

Recent Doppler backscattering applications in Globus-M tokamak

“…GAMs were identified in the spherical tokamak Globus-M [6,7] was discovered as coherent oscillations of perpendicular velocity in 20-35 kHz frequency range provided the backscatter region was located inside the separatrix [8][9][10]. This frequency range was in line with theoretical estimations performed for the conditions of the Globus-M periphery [11].…”

Tokamak research at the Ioffe Institute

“…Transport quantities and turbulence parameters were provided by the ELMFIRE gyrokinetic code. The modeling results have shown satisfactory agreement with the experiments: (1) in TUMAN-3M the GAM parameters threshold for L-H transition is determined (figure 4), however for FT-2 the transition was not possible for experimental GAM parameter sets [18]; (2) in the case of the pellet injection, L-H transition occurred if a part of the pellet was disintegrated in the pelletguide, resulting in a gas/'snow' puff so that the pellet ablation is peripheral; on the contrary, if the pellet is evaporated deeper in the plasma, there is no L-H transition [19].…”

Review of Advanced Implementation of Doppler Backscattering Method in Globus-M

“…DBS was implemented to study geodesic acoustic modes (GAMs) on the Globus-M tokamak in the Ohmic phase of discharges at relatively low plasma density (n ≈ (2-3) × 10 19 m −3 ) when the toroidal ion drift was directed away from the X-point [35][36][37]. All DBS systems (see Table 1) and in some experiments even their combinations were used to obtain information about various properties of GAMs presented in Table 3 (see the end of Section 3.1).…”

“…It was shown that an SMBI pulse can reduce the Doppler shift frequency, which corresponds to the flattening of the electric field. In a series of experiments on the EAST tokamak using two separate DBS systems, one for the Q-band (33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50) and the other for the V-band (50-75 GHz), Doppler shifted signals were obtained and radial profiles of perpendicular velocities were computed for the L-and H-mode [15]. In the Globus-M2 tokamak, the first results of the Doppler backscattering diagnostics during a discharge with the L-H transition show that the transition process is linked to the deformation of the poloidal rotation velocity profile [16].…”