Many colleagues from the radio-frequency power in plasmas (RFPP) community travelled to Hefei (China) last week (14th to 17th May) in order to attend the 23rd edition of the RFPP Conference. This conference tackles several aspects, from the engineering design of new antennas to the physics of the waves propagating inside a fusion plasma.
The Joint European Torus (JET) is getting ready for a new campaign with deuterium (D) fuel mixture at the Culham Centre for Fusion Energy (CCFE), UK. After this D campaign, a tritium (T) campaign is planned to follow. These campaigns are made in preparation for the eventual D-T campaign with a fusion reactor relevant 50%-50% D-T fuel mixture. It will be the second D-T campaign at JET; the first D-T campaign at JET was carried out in 1997. The production and physics of born alphas (He-4) at 3.5MeV due to D-T fusion reactions will be tested and assessed with the ITER-like-wall made of beryllium (Be) and tungsten (W).
As high-performance discharges are sought, the control of high-Z impurity transport will play a key role during this campaign. One of the main goals is to keep the impurity accumulation at the plasma core low. In this regard, large efforts have been carried out by the experimental and modelling team during the preparation of these campaigns.
Our group leader Dr. Mervi Mantsinen and PhD student Dani Gallart worked last week at the Max-Planck Institute for Plasma Physics (IPP) at Garching, Germany. They participated in the experiments on the ASDEX Upgrade (AUG) tokamak as part of the EUROfusion 2018 Medium Size Tokamak (MST1) experimental campaign.
Mervi was the scientific coordinator of the experiments that successfully proved the use of waves tuned to the third harmonic ion cyclotron resonance of deuterium (D) to heat the plasma. Various diagnostics including neutron detectors and neutral particle analysers confirmed the presence of energetic D ions accelerated by resonant wave-particle interaction.
The paper entitled “Modelling of JET hybrid plasmas with emphasis on performance of combined ICRF and NBI heating” has been published by Nuclear Fusion. It advances our understanding of the optimisation of fusion performance of the recent Joint European Torus (JET) hybrid plasmas. The hybrid scenario is an advanced regime of tokamak plasma operation expected to be applied in ITER. It is characterized by a low plasma current Ip which allows operation at a high normalised beta as well as a safety factor at the plasma centre greater than 1 which is beneficial from the plasma stability point of view.
The paper focuses on the impact of neutral beam injection (NBI) and specially ion cyclotron resonance frequency (ICRF) heating on the neutron production rate. The main scheme studied is minority hydrogen (H) in a deuterium (D) plasma with D beams. The modelling takes into account the synergy between ICRF and NBI heating through the second harmonic cyclotron resonance of D beam ions which allows us to assess its impact on the neutron rate RNT. Apart from the D scenario, the deuterium-tritium (DT) scenario is also assessed through an extrapolation of D high-performance hybrid discharges. These results are relevant for the forthcoming DTE2 campaign at JET where one of the goals is to achieve the highest possible fusion performance for a duration of more than 5 s.
One of the key requirements to achieve steady-state power production in a fusion reactor based on the so-called tokamak configuration is to generate non-inductive toroidal plasma current in an efficient way. A recent paper published in Physical Review Letters entitled “Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak” reports on the use of lower hybrid current drive (LHCD) as an efficient mean to obtain non-inductive plasma current at high plasma densities in a diverted tokamak configuration such as Alcator C-Mod.
Dr John Wright, Principal Scientist at Plasma Science and Fusion Center at MIT (USA) visited the BSC fusion group for two weeks in March, funded by BSC Severo Ochoa incoming mobility funding. The objective of his visit was to install the All-Orders Spectral Algorithm (AORSA) code at MareNostrum.