IEA Technology Collaboration Programme on Tokamak Programmes (CTP TCP)
Annual Briefing 2020
The objective of the CTP TCP is to advance the physics and technologies related to toroidal plasmas. This is achieved by strengthening cooperation among tokamak programmes, enhancing the effectiveness and productivity of the research and development (R&D) effort related to the tokamak fusion concept, contributing to and extending the scientific and technology database of toroidal confinement concepts, and providing a scientific and technological basis for the successful development of fusion power.
In 2020, the Covid-19 pandemic had a large impact on the international missions under the CTP TCP and there were very few assignments completed. Therefore, a large support was given for activities using remote participation tools and a lot of progress has been made using alternative approaches. These included, the successful remote participation in KSTAR (KO) experiments; the completion of the activities on the shattered pellet injection on JET, remote participation on DIII-D (US), EAST (CN) and KSTAR (KO) shattered pellet injection experiments, resonant magnetic perturbation experiments in KSTAR (KO) and ECCD breakdown optimisation experiments on DIII-D (US).
2. ChairÕs report 2020
The participation of Thailand is under discussion and observers from Thailand participated in the 10th Meeting of the Executive Committee. The representatives from Thailand were informed of the steps required for becoming members of the CTP TCP. However, in the latest iteration with the representatives from Thailand in August 2020, it was stated that the situation in Thailand has changed and that the process needed to be restarted with the new ministry. The members of the CTP TCP Exco unanimously agreed to wait for a clarification from Thailand regarding the request to join the CTP TCP and not to vote on this issue at this meeting. The Chair added that once the situation is clarified, the CTP TCP Exco would take a vote on this matter.
Regarding the invitation for Russia to participate in the CTP TCP, Russia has been invited to the CTP TCP some years ago and that efforts have been made to facilitate Russia joining the CTP TCP, including sending letters written by the CTP TCP Chair to the Russian contacts in at least 2 occasions. There have been iterations with contacts in the Russian Ministries, but these efforts did not lead to a positive outcome.
á 11th Executive Committee Meeting ITER HQ, France, Thursday 10th December 2020
á 23rd meeting of the International Tokamak Physics Activity Coordinating Committee (ITPA CC)
and 12th ITPA meeting for Joint Experiments ITER HQ, France, 8-9 December 2020
á The Disruptions workshop usually organised at Princeton was held via videoconference, in July 2020, under the IAEA. This workshop focussed on Disruption mitigation. The agreement is to continue to organise this meeting every year, alternating between the IAEA Disruptions Workshop and the Princeton Theory Workshop.
á The KSTAR conference, which usually takes place in January or February, the date has not been agreed yet, but it may take place in November or December 2021.
Three projects have been submitted to IEA regarding the Today in the Lab - Tomorrow in Energy? Initiative on: JET TAE Amplifier and Control Upgrade; Event Detection Intelligent Camera (EDICAM) for the JT-60SA Tokamak and JET Shattered Pellet Injection for Disruption Mitigation in ITER. The Event Detection Intelligent Camera (EDICAM) for the JT-60SA Tokamak was published by IEA. The Chair and Secretary participated in the TCP Chairs meeting on 8th October 2020.
Status report and milestones achieved
The ITER project continued to advance well in 2020 and a crucial milestone was achieved on May 27 2020, with the 1,250-tonne base of the cryostat successfully inserted into the Tokamak pit. This cryostat base, 30 metres in diameter, was positioned with a final tolerance under 3 mm at all metrology points. The cryostat lower cylinder was inserted on 31 August 2020 into the Tokamak Pit, fitting perfectly with the base. The delivery of the second European Toroidal Field Coil took place on 4 September 2020. With the delivery of the thermal shield sections from Korea, two toroidal field coils from Japan, and the vacuum vessel sector 6 from Korea, the first sector pre-assembly will start in 2021. Regarding the Poloidal Field Coils, Coil number 5 Winding Pack assembly is almost completed, the Coil number 2 is in preparation for Winding Pack impregnation, the Coil number 4 Double Pancakes winding has started; the Poloidal Field Coil number 6 arrived in June 2020 and preparations for cold test are almost completed. The fabrication of the Poloidal Field Coil number 1 in Russia is well advanced. The ITER Research Plan previously released publicly as a ITER Technical Report ITR-18-003 will be submitted to Nuclear Fusion in 2021. The ITER Research Plan will be formally included in the technical baseline to ensure consistency between hardware and research objectives in each phase.
Joint European Torus (JET), Axisymmetric Divertor Experiment (ASDEX) Upgrade, Tokamak ˆ Configuration Variable (TCV), Mega-Amp Spherical Tori (MAST) Upgrade, and Tungsten (W) Environment in Steady-state Tokamak (WEST)
The delays caused by the COVID-19 Pandemic were mitigated by remote scientific exploitation of JET and other European facilities. The first plasma was achieved on MAST Upgrade on 27th October 2020 marking an important milestone. MAST Upgrade is preparing to run initial physics experiments with over 3MW NBI power injected. The JET Shattered Pellet Injection experiments were successfully completed; performing disruption mitigation at high energy and providing unique data for ITER; with evidence that high-Z injection is not sufficient and deuterium pellets found to be efficient in mitigating Runway Electrons. Promising small ELM regimes for ITER and DEMO were found on TCV and ASDEX Upgrade with good core performance, with high fuelling and reduced magnetic shear at the plasma edge. The updated ITPA H-mode confinement database including the new data from JET ITER-like Wall and ASDEX Upgrade W-wall concluded that the confinement dependence on density and power degradation is weaker in metallic devices with weaker dependence on density, major radius, and stronger dependence on the plasma current with a projection to ITER predicting a 22% reduction in the energy confinement time with respect to the previous scaling. The manufacturing of the ITER-grade divertor components of the WEST Plasma Exhaust Upgrade has been completed. The JT-60SA EUROfusion-F4E joint activities are progressing well with the EDICAM wide-angle visible camera installed, 6 Enhancement Projects on-going and a strong and coordinated EU participation in the JT-60SA Integrated Commissioning.
The assembly of the upper part of the JT-60SA cryostat was completed; together with the final positioning of the centre solenoid. The assembly of the top lid thermal shield and the cryostat top lid was carried out and the assembling of the tokamak was completed on March 2020. The check of the vacuum tightness, and electrical ground and relative isolation for sub-assemblies has been carried out. On September 2020, the pumping down of the vacuum vessel and the cryostat started and both of them passed the leak tests. The cool down of the superconducting coils and the thermal shields started on October 2020, and all the superconducting coils have reached the superconducting state in November 2020. The coil energisation test will follow soon. After the coil energisation test, operation with plasma can start. On the basis of the trilateral agreement between the ITER organization (IO), F4E and QST, the information sharing on the assembly and integrated commissioning is effectively on going with the IO.
Experimental Advanced Superconducting Tokamak (EAST)
EAST long pulse high beta poloidal plasma operation in support of the CFETR 1GW scenario was obtained with 3.5 MW of radio frequency Heating and Current Drive in the tungsten upper divertor configuration, with improved energy confinement time by increasing the density peaking factor. Divertor detachment studies compatible with the grassy ELM regime considered in the CFETR design were performed providing a robust solution to achieve long-pulse high-performance H-mode operation with high heating power in a metal wall environment with several feedback control schemes, but without the use of Resonant Magnetic Perturbations as these are not foreseen for CFETR. Helium plasma experiments were performed in support of the ITER operation and Plasma Surface Interaction research. The upgrade of EAST is going on smoothly including new lower tungsten divertor with new geometry, improvement of the capability of heating systems, position rearrangement of heating and diagnostics with a new campaign planned from April 2021.
New Capabilities in HL-2A include a new Hard-X ray camera and Supersonic Molecular Beam Injection visualization. AlfvŽn Eigenmodes studies showed mode coupling generating multiple modes, which can cause resonance overlap in real and phase spaces and enhance transport and trigger avalanche events. Thresholds in terms of Electric Field and velocity shear were determined for both L-I and I-H transition and the velocity shear threshold was found independent of the plasma density and the total heating power.
SWIP has completed the installation and assembly of the HL-2M tokamak with the mission to develop the physics basis for advanced plasma scenarios with flexible divertors; to address burning plasma physics issues and advanced tokamak scenarios in support of future machines.
Korean Superconducting Tokamak Advanced Research (KSTAR)
In KSTAR, the access to high qmin >2 high beta scenarios has been expanded by early shaping, early heating and H-mode transition controlled by power injection to avoid instabilities. This strategy allows maintaining high qmin showing strong dependency of confinement on qmin and improved confinement with broader current profiles. Long pulses have been sustained for 30 seconds in hybrid scenarios, however, the performance gradually degraded mainly due to a drop in density and ion temperature. High ion temperature discharges in diverted L-mode edge with Upper Single node was sustained for 20 seconds in KSTAR with stable Internal Transport Barrier. This was achieved with almost fully non-inductive current drive with the loop voltage close to zero. ELM suppression was successful with an adaptive controller searching for an optimal level of Resonant Magnetic Perturbation. Two identical Shattered Pellet Injection systems were installed in toroidally opposite locations in KSTAR in collaboration with ITER-IO, ORNL, and KFE. Dual Shattered Pellet Injection experiments demonstrated the feasibility of simultaneous multiple injection as planned for ITER.
Spherical Torus at Seoul National University (VEST)
Internal Reconnection Events in disruptions studies found an experimental link between these ELM filaments and the occurrence of Internal Reconnection Events, suggesting new mechanisms for the interaction between the filaments and the internal modes that lead to the Internal Reconnection Events onset.
Doublet III D-shaped Tokamak (DIII-D)
DIII-D completed the helicon antenna commissioning and started to conduct experiments. Three new gyrotrons are planned to fill all available sockets. In a planned vent of the vacuum vessel, in the latter half of year, a new lower hybrid antenna will be installed.
National Spherical Torus Experiment Upgrade (NSTX-U)
The NSTX-U recovery project is proceeding with the delivery of six inner poloidal field coils, with three spare coils being fabricated. The new centre stack casing is now 80 % complete and first Plasma Facing component tiles have been delivered.
ADITYA-U experiments in 2020 focussed on Runaways, Disruptions, MHD Modulations and Plasma Rotation experiments. Disruption experiments showed faster current quench times at higher edge q. Electromagnetic Pellet Injection experiments showed that the current quench rate can be controlled by the amount of material injected. Experiments on the effect of gas-puff on runaway electrons showed reduction of the losses with suppression of edge fluctuations and it was shown that minor disruptions triggered by Supersonic Molecular Beam Injection causes runaway electron losses.
Steady State Superconducting Tokamak (SST-1)
SST-1 is preparing for operations with the new superconducting Poloidal Field coils later this year and no experimental campaigns took place in 2020.
Regarding the personnel assignments, and remote participation 2021, there are still uncertainties related to travel restrictions due to the covid-19 pandemic. However, a strong effort is directed to the participation in the commissioning of JT-60SA under the Broader Approach. The ITER-IO priorities relate to Shattered Pellet Injection experiments on DIII-D (US), KSTAR (KO) and ASDEX-U (EU) and participation on the JET experiments.