Speaker
Description
The deuterium experiment starts from March 2017 on the Large Helical Device (LHD). The deuterium experiment is a part of LHD performance upgrade project, including the upgrade of heating devices, the installation of closed helical diverter and the upgrade for diagnostic systems. The objectives of the deuterium experiment are:
- to realize high-performance plasmas in helical systems by confinement improvement and by upgraded facilities;
- to study the isotope effects on plasma confinement in toroidal plasma devices;
- to demonstrate the confinement capability of Energetic Particles (EPs) in helical systems; and
- to extend the research on the plasma-material interactions with long time scale using the benefits of the LHD’s steady state operation ability.
The preparation for the deuterium experiments has been started since March 2013 after the conclusion of the agreement for the environmental conservation and the LHD deuterium experiment between NIFS and the local government bodies. As a preparation for the experiment, the tritium removal system was installed based on this agreement. The removal system removes all of Hydrogen isotope gases by converting them to water using catalyst from the exhaust of vacuum pumping system for LHD and all of its peripheral devices. The system can be utilized for the detailed analysis of mass balance of Hydrogen isotopes in LHD using the tritium produced in the deuterium plasmas as a tracer. This will provide useful information for future fusion reactor in evaluating the fuel mass balance. The Integrated Radiation Monitoring System (IRMS) was also installed as a part of central interlock system of the LHD. The IRMS monitors all of the signals from environmental radiation monitoring detectors as well as the signals from neutron detectors in the torus hall. It also monitors the status of doors at the boundary of radiation controlled areas and the personnel access to the areas through the access control system.
The two of Positive-ion based Neutral Beam Injectors (P-NBIs) were upgraded to improve their injection power from 6MW to 9MW by increasing their injection energies. The two of micro wave launchers for Electron Cyclotron Heating (ECH) were moved from the upper port to the outer port close to the mid plane to increase the efficiency of ECH.
Three sets of neutron detectors, which consist of one fission chamber and one 3He (or 10B) proportional chamber, were installed as neutron flux monitors for LHD and the absolute calibration experiment for the detectors was performed using a 252Cf neutron source in November 2016 as a part of commissioning for the LHD deuterium experiment.
In the presentation, the preparation and the commission for the LHD deuterium experiment will be discussed.
| Eligible for student paper award? | No |
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