Dr Sergei Sharapov (CCFE)
A deuterium-tritium (D-T) experimental campaign DTE2 on JET scheduled for 2019-2020,will be done in the Be/W vessel and will address essential operational, technical, diagnostic and scientific issues in support of ITER . In preparation for the campaign, developments were performed on JET aiming at studies of alpha-particles. For studying AEs driven entirely by alpha-particles, a scenario similar to the TFTR beam “afterglow”  was developed for JET. In DT plasmas, after NBI is switched off, alpha-particles will be the only energetic ions during time interval between slowing-down times for NBI-produced ions and alpha-particles. Detection of alpha-driven AEs in this time window may help in diagnosing the temporal evolution of the pressure profile and slowing-down time of alpha-particles. JET advanced tokamak scenarios with q ≈ 1.5-2.5 were chosen and discharges have been successfully developed. The transport modelling extrapolated to DT predicted that alpha-particle beta of ≈ 0.1% could be achieved comparable to that in successful TFTR experiments. In “hybrid” scenario plasmas with q0 ≥ 1, fast ion losses in the MeV energy range were observed during n=1 fishbones driven by a resonant interaction with D beam ions in the energy range ≤ 120 keV . The losses are identified as an expulsion of D-D fusion products, 1 MeV tritons and 3 MeV protons. A mode analysis with the MISHKA code combined with the study of nonlinear wave-particle interaction with HAGIS show that the loss of toroidal symmetry strongly affects the confinement of high energy tritons and protons by perturbing their orbits and expelling them in a good agreement with experiment. The extrapolation to the case of alpha-particles in DTE2 hybrid scenarios with similar fishbones has shown an additional alpha-particle loss of ~ 1% . References:  Weisen H et al., Fus. React. Diag., AIP Conf. Proc. 1612, 77-86 (2014);  Nazikian R et al., PRL 78, 2976 (1997);  Fitzgerald M et al, submitted to Nucl. Fusion (2018).
|Country or International Organization||United Kingdom|
Dr Sergei Sharapov (CCFE)
Dr Clive Challis (Culham Centre for Fusion Energy) Dr Damian King (CCFE) Dr Emmanuel Joffrin (CEA/IRFM) Dr Fernando Nabais (IST) Mr Henri Weisen (JET EFDA) Dr Joelle Mailloux (CCFE) Dr Jorge Ferreira (IST) Dr Massimo Nocente (Dipartimento di Fisica, Università di Milano-Bicocca) Prof. Mervi Mantsinen (BSC) Dr Michael Fitzgerald (CCFE) Dr Pablo Vallejos (KTH) Dr Paulo Puglia (EPFL) Dr Remi Dumont (CEA) Dr Thomas Johnson (KTH) Dr Valentin Aslanyan (MIT) Dr Vasili Kiptily (CCFE)