The understanding of the physics underlying the L-H transition has strong implications for ITER experimental reactor and demonstration power plant (DEMO). In many tokamaks, including JET, it has been observed that, at a particular plasma density, n (e,min), the power necessary to access H-mode PL-H is minimum. In the present work, L-H transitions of JET deuterium plasmas heated by neutral beam injection (NBI) are studied for the first time by means of a power balance analysis to characterize the main contributions in the transition, through integrated transport modelling. In the pulses analysed, we do observe a minimum of the L-H power threshold in density, indicating the presence of density branches and of n (e,min). Electron and ion heat fluxes at the transition are estimated separately. The electron\/ion equipartition power results in favour of the ions, as shown by QuaLiKiz quasilinear gyrokinetic simulations, which predict a larger ion transport that causes T (e) > T (i). The resulting edge ion heat flux also shows a clear change of slope below n (e,min), similarly to ASDEX-Upgrade (AUG) NBI pulses (Ryter et al 2014 Nucl. Fusion 54 083003). JET NBI data are compared to radio-frequency heated AUG and Alcator C-mod pulses (Schmidtmayr et al 2018 Nucl. Fusion 58 056003), showing a different trend of the power, coupled to ions at the L-H transition with respect to the linearity observed in the radio-frequency heated plasmas. The presence of n (e,min) and the role of the ion heat flux is discussed in the paper, although it seems it is not possible to explain the presence of a PL-H minimum in density by a critical ion heat flux and by the equipartition power for the JET NBI-heated plasmas analysed.<\/p>\n","protected":false},"excerpt":{"rendered":"
Vincenzi P.; Solano E.R.; Delabie E.; Bourdelle C.; Snoep G.; Baciero A.; Birkenmeier G.; Carvalho P.; Cavedon M.; Chernyshova M.; Citrin, J.; Fontdecaba J.M.; Hillesheim J.C.; Huber A.; Maggi C.; Menmuir S.; Parra F.<\/p>\n","protected":false},"featured_media":1294,"comment_status":"closed","ping_status":"open","template":"","meta":[],"product_cat":[574],"product_tag":[765,822,4213,4214,4215],"class_list":["post-9390","product","type-product","status-publish","has-post-thumbnail","hentry","product_cat-journal-articles","product_tag-h-mode","product_tag-jet","product_tag-l-h","product_tag-power-balance-analysis","product_tag-ion-heat-flux","prodpage-style2"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.istp.cnr.it\/it\/wp-json\/wp\/v2\/product\/9390","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.istp.cnr.it\/it\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/www.istp.cnr.it\/it\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/www.istp.cnr.it\/it\/wp-json\/wp\/v2\/comments?post=9390"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.istp.cnr.it\/it\/wp-json\/wp\/v2\/media\/1294"}],"wp:attachment":[{"href":"https:\/\/www.istp.cnr.it\/it\/wp-json\/wp\/v2\/media?parent=9390"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.istp.cnr.it\/it\/wp-json\/wp\/v2\/product_cat?post=9390"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.istp.cnr.it\/it\/wp-json\/wp\/v2\/product_tag?post=9390"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}