Neutral beam heating on the TCV tokamak 29th Symposium on Fusion Technology, 5 - 9 September 2016, Prague, Czech Republic Neutral beam heating on the TCV tokamak Alexander N. Karpushova, René Chavana, Stefano Codaa, Vladimir I. Davydenkob, Frédéric Dolizya, Aleksandr N. Dranitchnikovb, Basil P. Duvala, Alexander A. Ivanovb, Damien Fasela, Ambrogio Fasolia, Vyacheslav V. Kolmogorovb, Pierre Lavanchya, Xavier Llobeta, Blaise Marletaza, Philippe Marmilloda, Yves Martina, Antoine Merlea, Albert Pereza, Olivier Sautera, Ugo Siravoa, Igor V. Shikhovtsevb, Aleksey V. Sorokinb, Matthieu Toussainta a Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC),CH-1015 Lausanne, Switzerland b Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk, Russia Introduction I. Neutral Beam Injector TCV tokamak: RO0.88m, a0.25m, BT1.54T, IP1MA, in operation since 1992 before 2016: 0.7≤ne≤151019m-3; 0.3≤Te≤15keV; 0.15≤Ti≤1keV; Ti/Te:0.1…0.8 flexible shaping: elongation () up to 2.8, positive and negative triangularity (=-0.7…+1.0) 4MW/2s real time-controllable ECH-ECCD system, since 2000: X2 (ne≤4.21019m-3, cut-off) and X3 (ne≥3.51019m-3) continuous improvements in diagnostics and plasma control Motivation for upgrades — widening the parameter range of reactor relevant regimes Direct ion heating: 1 MW, 25 keV, deuterium neutral beam (installed in 2015, in experiment from 2016) access to Ti/Te≥1 (up to 3…5), including reactor relevant Te/Ti1, Ti up to 2…4keV 1 MW, 50-60 keV, neutral beam (2018) fast ion physics, optimized for high density plasma, especially in H-mode ECH upgrades: two new X3/X2, replacing two X2 (2015-2018) X3: 1.35MW  3.50MW 30.50MW/118GHz + 21MW/126&84GHz (dual frequency) X2: 2.70MW  4.85MW 30.45MW/82.7GHz + 21MW/126&84GHz + 20.75MW/84GHz  high  (ITER scenarios), lower collisionality II. Power sweep and modulation Neutral Beam Injector on TCV 6.6 6.4 6.2 6.0 5.8 5.6 1.08 1.13 1.18 1.23 1.28 1.33 1.38 Perveance (I/U3/2), ×105 A×V3/2 Beam width (cm) on calorimeter vs ion current Optimization at 4-6 power levels: perveance scan divergence minimum at fixed energy beam energy, RF power (ion current), suppression grid voltage, BM current UHV(energy), Ii(ion current)  functions of PO. interpolation between “optimization” points Control signals (DACs) - f(UHV, Ii, Mi, time)[Volts] Ion Source 30kV, 50A, deuterium 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 Time, sec Pion: 290kW→1.22MW PO: 230kW→1.05MW EO: 15→25keV Iion: 19→49A IO: 17→42eq.A NBI shot #1678 (2015-12-10 11:58:46) 1.2 1.0 0.8 0.6 0.4 0.2 Power, MW Energy, keV 50 40 30 20 10 Current, A 25 15 5 Beam energy vs neutral beam power 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Neutral Power, MW 25 24 23 22 21 20 19 18 17 16 15 Energy, keV NBI shots #1675…1678 Injector layout: 1 – RF plasma source, 2 – magnetic screen, 3 – ion-optical system, 4 – neutral beam; 5 –adjusting device; 6 – ions source gate-valve; 7 – vacuum tank; 8 – cryopump cold head; 9 – liquid nitrogen volume; 10 – cryo-panels, 11 – neutralizer, 12 – bending magnet, 13 – diaphragm, 14 – ion dump for positive ions, 15 – calorimeter. Plasma Source inductively driven 40kW 4 MHz RF-discharge Neutral beam power fractions 76:17:7%, 24.8kV, deuterium Ion Optical System 3 spherical copper grids Ø250mm, focal length 3.6m NBI power steps with 5 ms transition time 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Time, sec 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 Power, MW NBI shots #1677, 1734…1743 (2015-12-11) NBI power modulation 200 Hz @ 730 kW and sweep 50 Hz 840/530 kW and (neutral power) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Time, sec 0.85 0.80 0.75 0.70 0.65 0.60 0.55 Power, MW NBI shots #1723…1732 (2015-12-11) III. First shots with NB heating Before NB heating: NBI assembling and preliminary tests – June-August 2015; Modification of calorimeter, integration with TCV – September-November 2015 NBI tests and optimisation on the calorimeter – December 2015 – January 2016 Tests of TCV first wall overheat protection system. First experiments with NB plasma heating: Beam duct cleaning – a few shots into plasma 50…200ms 5th NB shot in TCV plasma #051458, 29.01.2016 L-mode, plasma current IP:-240kA; 1.03 MW, 25 keV, deuterium, 0.52 sec. Preliminary observations: Ion (and electron) heating, increase of the plasma energy; Strong increase of toroidal rotation; Plasma fueling, limitation on plasma density. PNBI: 1.03 MW “ion power””neutralization efficiency” POH: 295→180→300 kW Plasma energy (WP, DML): 8→14→7kJ Bulk ion energy (Wi, CXRS): 3.5→6.5→2.5kJ Electron energy (We, TS): 3→6→3kJ Bulk energy (Wi+We): 8→13→6kJ Fast ions: ~1kJ IP: -240 kA favorable for fast ion first orbit losses neL: 3.91019 m-2 ne(0): 5.81019 m-3 shine-through ≤ 0.5% VI. NBI in EUROfusion MST1-TCV experiments 580 TCV shots with NB heating, since 27.01.2016 > 60% of experiments (program) requested NBH, 20 of 33 missions ~ 25% of TCV shots with NBH, availability – 85-90% 7-10% faults of control electronics and power supplies 0.3% breakdowns in ion optics per shot Experimental results and observations: ion temperature ×2–4, up to 2-2.5keV in L-mode, 2.5-3.5keV in H-mode (with 1MW NBI) CO-NBI toroidal rotation 100–300 km/s, -30…+30km/s without beam easier access of H-mode, control of sawtooth and ELM frequency Electron temperature: 0.9→1.2→0.9keV 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 Plasma radius,  2.0 1.5 1.0 0.5 Electron temperature (Thomson scattering), keV Ion temperature: 0.65→2.0→0.55keV 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 Plasma radius,  2.0 1.5 1.0 0.5 Ion temperature (CXRS, CVI), keV 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 Plasma radius,  Electron density (Thomson scattering), ×1019m-3 7 6 5 4 3 2 1 Toroidal rotation (CXRS) +20→-160→+15 km/s 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 Plasma radius,  Ion temperature (CXRS, CVI), keV 40 -40 -80 -120 -160 Ion temperature: 0.35→3.7→0.5keV 0 0.2 0.4 0.6 0.8 1.0 Plasma radius,  4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 Ion Temperature, keV TCV #53362 Electron temperature: 1.1→1.4→0.9keV 0 0.2 0.4 0.6 0.8 1.0 Plasma radius,  2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 Electron Temperature, keV TCV #53362 NB heating in ELMy H-mode Close to ASTRA prediction – Te/Ti:1.3/1.9keV in A.N.Karpushov, et al.; Upgrade of the TCV tokamak, first phase: Neutral beam heating system; Fusion Engineering and Design, (2015) DOI:10.1016/j.fusengdes.2015.01.052 References: A. Fasoli for the TCV Team; TCV heating and in-vessel upgrades for addressing DEMO physics issues; Nucl. Fusion 55 (2015) 043006; DOI:10.1088/0029-5515/55/4/043006 A.N.Karpushov, et al.; Upgrade of the TCV tokamak, first phase: Neutral beam heating system; Fusion Engineering and Design 96–97 (2015)493–497; DOI:10.1016/j.fusengdes.2015.01.052 Alexander N. Karpushov, Basil P. Duval, René Chavan, Emiliano Fable, Jean-Michel Mayor, Olivier Sauter, Henri Weisen; A scoping study of the application of neutral beam heating on the TCV tokamak; Fusion Engineering and Design, 86 (2011) 868–871 DOI:10.1016/j.fusengdes.2011.02.077 M. Toussaint, et al.; Beam duct for the 1 MW neutral beam heating injector on TCV, P3.27 (this conference) D. Fasel, et al.; Commissioning of the heating neutral beam injector on the TCV tokamak, P3.28 (this conference) Acknowledgements The authors are very grateful to Manfred Sauer (ex. Inst. fur Plasmaphys., Forschungszentrum Julich GmbH) for participation in the NBI installation and commissioning on the TCV, to Dr. David L. Keeling and Tim Robinson (EURATOM/CCFE Fusion Association, Culham Science Centre) for useful discussions and help with NBI operation during EUROfusion MST1 campaign, to members of SPC-EPFL and Budker INP teams involved in the work on manufacturing, installation, commissioning and operation of heating beam. This work supported in part by the Swiss National Science Foundation. E-mail address: alexander.karpushov@epfl.ch