Overview of the TCV tokamak experimental programme

Abstract

The tokamak à configuration variable (TCV) continues to leverage its unique shaping capabilities, flexible heating systems and modern control system to address critical issues in preparation for ITER and a fusion power plant. For the 2019–20 campaign its configurational flexibility has been enhanced with the installation of removable divertor gas baffles, its diagnostic capabilities with an extensive set of upgrades and its heating systems with new dual frequency gyrotrons. The gas baffles reduce coupling between the divertor and the main chamber and allow for detailed investigations on the role of fuelling in general and, together with upgraded boundary diagnostics, test divertor and edge models in particular. The increased heating capabilities broaden the operational regime to include T e/T i ∼ 1 and have stimulated refocussing studies from L-mode to H-mode across a range of research topics. ITER baseline parameters were reached in type-I ELMy H-modes and alternative regimes with ‘small’ (or no) ELMs explored. Most prominently, negative triangularity was investigated in detail and confirmed as an attractive scenario with H-mode level core confinement but an L-mode edge. Emphasis was also placed on control, where an increased number of observers, actuators and control solutions became available and are now integrated into a generic control framework as will be needed in future devices. The quantity and quality of results of the 2019–20 TCV campaign are a testament to its successful integration within the European research effort alongside a vibrant domestic programme and international collaborations.

Improved heat and particle flux mitigation in high core confinement, baffled, alternative divertor configurations in the TCV tokamak

“…These experiments are carried out at the TCV tokamak, which is a carbon walled, medium-sized tokamak (major radius, R 0 = 0.88 m, minor radius, a = 0.25 m) with unique flexibility to vary the plasma shape, using 16 independently controlled poloidal field coils [46,52,55]. Figures 1(a)-(c), shows the poloidal magnetic geometry of the SN (in red), the XD (in blue), and the XPT (in green) along with radial profiles of their f x and L in (d) and (e) respectively.…”

Investigating the impact of the molecular charge-exchange rate on detached SOLPS-ITER simulations

“…A visualisation of the TCV vessel geometry, fluid grid (red), Eirene grid (black/grey), spectroscopic (DSS) lines of sight (green), outer divertor fluid grid cells (blue shading), separatrix fluid grid cells (cyan), D 2 fuelling location (cyan) and Langmuir probe (LP) location (magenta). [21,22], discharge # 52065, which is a single null L-mode unbaffled [23,24] density ramp discharge that has been extensively reported in literature [3,7,5,9,25,26].…”

X-point and divertor filament dynamics from Gas Puff Imaging on TCV

“…The Tokamak à Configuration Variable TCV (major radius R 0 = 0.88 m, toroidal field B T ≤ 1.45 T) [31] is equipped with many edge turbulence diagnostics. Over 180 wall-embedded Langmuir Probes (LP) [32,33], a reciprocating probe (RCP) [8] at the outboard midplane and a Reciprocating Divertor Probe Array (RDPA) [34] allow for 1D and 2D fluctuation measurements of ion saturation current, floating potential and parallel Mach number in the midplane SOL and divertor, respectively.…”