Estimate of 3D power wall loads due to Neutral Beam Injection in EU DEMO ramp-up phase

• Published in: Nuclear materials and energy Vol. 18; pp. 188 - 192
• Main Authors: Vincenzi, P., Varje, J., Agostinetti, P., Artaud, J.F., Bolzonella, T., Kurki-Suonio, T., Mattei, M., Sonato, P., Vallar, M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2019; Elsevier
• ISSN: 2352-1791; 2352-1791
• DOI: 10.1016/j.nme.2018.12.031

•NBI usability in DEMO1 ramp-up phase may be barely possible at low plasma density.•NBI shine-through losses can exceed the tolerable first wall heat flux limit.•Up to 29% shine-through losses (peak power of 1.1 MW/m2) are found during ramp-up.•With ITER criteria, DEMO NBI could be switched on in ramp-up at  ∼ 1.3 × 1019 m−3.•DEMO NBI operational window can be therefore enlarged to ramp-up phase. Heating and current drive systems such as high energy Neutral Beam Injection (NBI) are being considered for pulsed EU DEMO (“DEMO1”) pre-conceptual design. Their aim is to provide auxiliary power, not only during flat-top, but also during transient phases (i.e. plasma current ramp-up and ramp-down). In this work, NBI fast particle power loads on DEMO1 first wall, due to shine-through and orbit losses, are calculated for the diverted plasma ramp-up phase. Numerical simulations are performed using BBNBI and ASCOT Monte Carlo codes. The simulations have been done using a complete 3D wall geometry, and implementing the latest DEMO NBI design, which foresees NBI at 800 keV particle energy. Location and power density of NBI-related power loads at different ramp-up time steps are evaluated and compared with the maximum tolerable heat flux taken from ITER case. Since NBI shine-through losses (dominant during low density phases) depend mainly on the beam energy, plasma density and volume, DEMO has a more favourable situation than ITER, enlarging NBI operational window. Using ITER criteria, DEMO NBI at full energy and power could be switched on during ramp-up at ~ 1.3 × 1019 m-3. This increases the appeal of neutral beam injectors as auxiliary power systems for DEMO.