Recent progress in L–H transition studies at JET: tritium, helium, hydrogen and deuterium. (1st July 2022)

• Record Type: Journal Article
• Authors: Solano, E.R.; Delabie, E.; Birkenmeier, G.; Silva, C.; Hillesheim, J.C.; Vincenzi, P.; Nielsen, A.H.; Rasmussen, J.Juul; Baciero, A.; Aleiferis, S.; Balboa, I.; Boboc, A.; Bourdelle, C.; Carvalho, I.S.; Carvalho, P.; Chernyshova, M.; Coelho, R.; Craciunescu, T.; Dumont, R.; Dumortier, P.; Luna, E.de la; Flanagan, J.; Fontana, M.; Fontdecaba, J.M.; Frassinetti, L.; Gallart, D.; Garcia, J.; Giovannozzi, E.; Giroud, C.; Gromelski, W.; Henriques, R.; Horvath, L.; Jacquet, P.; Jepu, I.; Kappatou, A.; Keeling, D.L.; King, D.; Kowalska-Strzęciwilk, E.; Lennholm, M.; Lerche, E.; Litherland-Smith, E.; Kiptily, V.; Kirov, K.; Loarte, A.; Lomanowski, B.; Maggi, C.F.; Mantsinen, M.J.; Manzanares, A.; Maslov, M.; Meigs, A.G.; Monakhov, I.; Morales, R.B.; Nina, D.; Noble, C.; Parail, V.; Diaz, F.Parra; Pawelec, E.; Pucella, G.; Réfy, D.; Righi-Steele, E.; Rimini, F.G.; Robinson, T.; Saarelma, S.; Sertoli, M.; Shaw, A.; Silburn, S.; Sirén, P.; Štancar, Ž.; Sun, H.; Szepesi, G.; Taylor, D.; Tholerus, E.; Vartanian, S.; Verdoolaege, G.; Viola, B.; Weisen, H.; Wilson, T.; Contributors, JET;
• Is Part Of: Nuclear fusion. Volume 62:Number 7(2022)
• Publication Date: 2022-07-01
• Subjects: L–H transition -- tritium -- helium -- isotope; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/ac4ed8
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: We present an overview of results from a series of L–H transition experiments undertaken at JET since the installation of the ITER-like-wall (JET-ILW), with beryllium wall tiles and a tungsten divertor. Tritium, helium and deuterium plasmas have been investigated. Initial results in tritium show ohmic L–H transitions at low density and the power threshold for the L–H transition ( P LH ) is lower in tritium plasmas than in deuterium ones at low densities, while we still lack contrasted data to provide a scaling at high densities. In helium plasmas there is a notable shift of the density at which the power threshold is minimum ( n ¯ e, min ) to higher values relative to deuterium and hydrogen references. Above n ¯ e, min (He) the L–H power threshold at high densities is similar for D and He plasmas. Transport modelling in slab geometry shows that in helium neoclassical transport competes with interchange-driven transport, unlike in hydrogen isotopes. Measurements of the radial electric field in deuterium plasmas show that E r shear is not a good indicator of proximity to the L–H transition. Transport analysis of ion heat flux in deuterium plasmas show a non-linearity as density is decreased below n ¯ e, min . Lastly, a regression of the JET-ILW deuterium data is compared to the 2008 ITPA scaling law.