29th Symposium on Fusion Technology (SOFT 2016)

P3.030 Neutral beam heating on the TCV tokamak

7 Sep 2016, 11:00

1h 20m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 30

Poster B. Plasma Heating and Current Drive P3 Poster session

Speaker

Alexander N. Karpushov (Swiss Plasma Center (SPC))

Description

The TCV tokamak contributes to physics understanding in fusion reactor research based with a wide experimental tool set: flexible shaping and high power electron cyclotron heating. Plasma regimes with high plasma pressure, a wide range of temperature ratios and significant populations of fast ions are now attainable by a TCV heating system upgrade. In the first stage of the TCV upgrade program, a 1 MW neutral beam of Deuterium or Hydrogen [2] was installed (final acceptation, early 2016), and is reported in this paper. Recently, during commissioning of the first injector (NBI) [3], 1 MW of power was delivered into plasma, at energies ranging from 15-26 keV. Record ion temperatures of 2 keV and toroidal rotation velocities up to 160 km/s were promptly observed within a few discharges. A plasma box with up to 40 kW of RF power at ~4 MHz forms the NBI plasma source. A slit-geometry in the elementary cell of injector ion optics was adopted; high aspect ratio slits, orientated in the horizontal plane, distributed inside a 250 mm radius circle. To focus the beam to the design location (~3.6 m from the ion source), the grids consist of spherical segments. An angular divergence of 20 mrad across and 12 mrad along the slits was achieved. Finally, the NBI control and power supply systems are described that allow variation and fast modulation of the NBI power. This work was supported in part by the Swiss National Science Foundation. [1] A. Fasoli for the TCV Team, Nucl. Fusion 55 (2015) 043006 [2] A N. Karpushov et al., Fusion Engineering and Design 96-97 (2015) 493 [3] A N. Karpushov et al., Fusion Engineering and Design 86 (2011) 868