Heating Issues. G.Granucci on behalf of the project team

Transcription

1 Heating Issues G.Granucci on behalf of the project team EURO fusion DTT Workshop Frascati, Italy, June 2017

2 Summary Physical Requirements DTT Heating Mix ECRH System ICRH System Auxiliary Heating Systems Installation Timing Conclusion The NNBI System will be described in next presentation by P. Sonato

3 Physical Requirements for DTT Heating Systems The main tasks for DTT Heating System are to supply the power to reach the prescribed P sep /R of 15 MW/m and to sustain a robust H- mode. This requires a reference amount of ~45 MW of P AUX. Three Heating system are considered: ICRH, ECRH and NNBI Main Physical requirements are: Bulk electron/ion heating for H-mode: Current profile tailoring with localized CD: Pulse extension by assisting current ramp-up: Avoid central impurity accumulation: Sawtooth and NTM control: Plasma Current Sustainment: Fast particle simulation: NNBI, EC, IC EC EC EC, IC EC NNBI, EC IC, NNBI

4 DTT Heating Mix The required 45 MW at plasma can be assured in different ways, depending on different considerations as: performances, costs, availability, engineering compatibility The Report Scenario was in two steps (installed power): 1 st 24 MW* of IC and 12 MW of EC; full available in 2 years 2 nd - 15 MW of NNBI to be decided after 1 year A New Scenario is : 1 st - 24 MW* of IC and 16 MW of EC full available in 2 years 2 nd -15 MW of NNBI + 12 MW of EC in 5 year from plasma start * 10 MW at plasma or up to 17 MW in case of positive tests on EBG antenna.

5 EC System Main Features Cluster approach (4 gyrotron for single HVPS) Multi Beam Quasi optical Transmission line: 6 beams x line Dedicated (straight) layout to access to DTT CD Efficiency vs deposition Upper Launcher GRAY code Two different plug-in in launchers: 1 RT front steering launcher (4MW) from upper port for NTM stabilization and control; 3 Simplified Front Steering launchers (4MW) from Equatorial Ports; In the Report EC Launchers were at fixed toroidal direction, in case of more CD flexibility required, symmetric solutions will be studied

6 ECRH System: Source Issue Reference Gyrotron: 170 GHZ, 1 MW, cw already developed for ITER with High reliability and efficiency (~50%) The EU 170 GHz gyrotron at SPC test-bed For more flexibility in magnetic field a double frequency gyrotron can be considered: 140 GHz and 170 GHz The ECRH system will be designed using same concepts under study for DEMO EC system (WPHCD) applying a similar simplicity and the high reliability required.

7 Concepts for EC Systems 3 plug-in EC equatorial launchers 4 open-ended waveguides launch to individual ellipsoidal focusing movable mirrors Multi Beam Quasi Optical Evacuated TL Up to 6 beams are transmitted by set of focussing + plane mirrors (see W7-X) eventually under vacuum (as for DEMO) 1 plug-in EC Upper Launcher Concepts Toroidal steering

8 ICRH System Characteristics Heating scheme for H-mode reference 6 T scenario: H minority heating ω c ~ 90 MHz at plasma centre, 3 He minority heating ω c ~ 60 MHz at plasma centre. 16 transmitters based on a 3-stage amplification TH526 by Thales Electron Devices, able to deliver: 24 MW at 60 MHz or 21 MW at 90 MHz for 100s of pulse. A factor 1.3 can be applied in case of pulse < 30 s ~32 60MHz Transmission lines and matching: Matching circuit based on external conjugate-t junctions 3-dB hybrid couplers as possible future upgrade. Coaxial lines with 50(30) Ω impedance before(after) conjugate-t and 13.4 Ω antenna feeders 4 Antennas Baseline design: shimming port-plugged antenna, 2(H) x 4(V) straps fed by 8 coaxial through ~ 0.65m x 1.1m port. Coupled power limited by voltage standoff according to TOPICA simulations Conservative 4 MW /m 2 assumed ~11 MW coupled to plasma

9 ICRH alternative antenna designs Three-strap (AUG-like) antenna to balance image currents: requires wider antenna P_central / P_outer = 1.5 TOPICA code improvement to 4 MW feasible with optimization EBG antenna concept: periodic structures (Electromagnetic Band Gap ) behind the straps, acting as high impedance surfaces lead to reflected power < -10 db and low standing wave ratios in the feeders Thermo-mechanical analyses is required Possible first demonstrative test on EAST. If positive EBG will be adopted in DTT h=12 cm h=11 cm h=10 cm h=9 cm h strap Resonance frequency tuneable in MHz by varyng h

10 RF System Timeline EC IC

11 Conclusion DTT RF Heating Systems will exploit R&D already done for ITER and W7-X Some R&D activity (double frequency gyrotron and EBG antenna) will be addressed quickly in order to avoid delay in procurement The Power installation will be articulated in two steps: First 5 years : from 26 MW to 33 MW depending on EBG From 6 Th year : extra 10 MW of NNBI and 10 MW of EC and pulse length Present stage is a pre-conceptual phase: new input can be easily included and/or power mix modified