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An international journal of news from the stellarator community
Editor: James A. Rome Issue 173 April 2021
E-Mail: Phone: +1 (865) 482-5643
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4th LHD Workshop
The 4th Large Helical Device (LHD) workshop was held
18–19 March 2021 via Zoom. Usually, this workshop
takes place at the National Institute of Fusion Science, and
many colleagues discuss newly obtained results from the
LHD experiment face-to-face. Unfortunately, due to the
pandemic of COVID-19, the workshop was organized as a
virtual workshop via the video conference system.
Approximately 120 participants joined the workshop,
including about 40 collaborators worldwide from Europe,
the United States, China, and other Japanese labs. Many
exciting results were presented and intensively discussed
from the perspective of the next LHD campaign during the
two days.
The first day featured mission-oriented topics for further
extension of the operational space, including the simultaneous
achievement of high ion and electron temperatures,
the achievement of complete detachment, and core confinement
improvement of long-pulse discharges as facilitated
by electron cyclotron (ECH) and ion cyclotron (ICH)
heating. Afterwards, energetic particle physics, advanced
diagnostics, turbulent transport, and plasma-wall interaction
issues were discussed. Especially in the evening,
many German colleagues gave presentations, and so, we
had essential discussions comparing LHD and Wendelstein
7-X (W7-X) results.
In the morning of the second day, we had discussions
about topics on collaborations with US colleagues, emphasizing
two newly installed resources: the IPD (Impurity
Powder Dropper) and FIDA (Fast Ion D-Alpha spectroscopy)
based on the negative ion source. In the IPD experiments,
a clear change of turbulent transport during
dropping of the impurity powder was observed. This result
can lead to optimization of long-pulse discharges in stellarators.
Also, the FIDA in LHD is the only such system in
the world because LHD is the only device in which a negative
ion source neutral beam injector can routinely inject
into a high-performance plasma. Testing of the FIDA in
JT-60SA, and eventually ITER, is also an important topic.
At the end of the workshop, the European colleagues
reported the international collaboration supported by
EUROfusion, and the future strategic planning of LHD
collaboration with the world was discussed. Many essential
comments and ideas were presented, and these will
give a basis and perspective to the organization of the 23rd
Yasuhiro Suzuki (Secretary of the Workshop)
National Institute for Fusion Science, Japan
Fig. 1. Screenshot of participants on Zoom instead of the traditional
“group photo.”
In this issue . . .
4th LHD Workshop
The 4th LHD workshop was held 18–19 March 2021 to discuss
new results obtained during the 22nd campaign of LHD and
future strategic planning. .......................................................1

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