1. Status and Plans at LHD Y. Takeiri for LHD Experiment Group
National Institute for Fusion Science,
National Institutes of Natural Sciences, Japan
SOKENDAI, Japan
Thank you Mr. Chairman.
I would like to make a report on the status and plans at LHD, Large Helical Device at the NIFS, National Institute for Fusion Science, Japan.
Fusion Power Associates, 37th Annual Meeting and Symposium
FUSION POWER DEVELOPMENT: AN INTERNATIONAL VENTURE
December 13-14, 2016, Hyatt Regency Capitol Hill Hotel, Washington, DC

2. Large Helical Device (LHD)
One of the largest superconducting devices
LHD is optimized heliotron with continuous helical coils.
The superconducting magnets have been operated since 1998 without any severe cryogenic troubles.
Specification
 Helical mode numbers: l/m=2/10
 All superconducting coil system
 Plasma major radius: m
 Plasma minor radius: m
 Plasma volume: m3
 Toroidal field strength: 3 T
 20 RMP coils
Heating Systems
 negative-NBI x 3
H-inj. 180 keV, 16MW
 positive-NBI x 2
H-inj keV, 12MW
 ECH (77 GHz x 3, 154 GHz x 2, 82.7 GHz, 84 GHz), 5.4MW (0.6 MW CW)
 ICH (20 –100 MHz) x MW
The Large Helical Device, LHD, was the world largest superconducting helical device, and now one of them after the start of Wendelstein 7-X experiment.
LHD is optimized heliotron with continuous helical coils, characterized by currentless, i.e., disruption-free plasma adding capability of steady-state operation.
This large-scale superconducting magnets have been operated since 1998, without any severe cryogenic troubles. LHD is equipped with three kinds of heating systems, NBI system with 3 negative-ion-based injectors and 2 positive-ion-based injectors, ECH system with powerful gyrotrons, and ICH system mainly utilized for long-pulse discharge. These heating systems have much contributed to wide-ranging parameter extension and physics experiments.

3. Contents 1. Significance of LHD in the world fusion research
2. Recent progress:
Extension of operational regime
Particle balance in steady-state plasmas
3. Deuterium experiment
Objects
Schedule
Upgrade of facilities (e.g., negative-ion based NBI)
Neutron calibration experiment (Nov.)
International Program Committee
4. Summary
Here are contents of my report today.
After a short introduction on LHD emphasizing the significance in the world fusion research, recent progress is presented focusing the extension of operational regime and the progress of particle balance study in steady-state plasmas.
Then, I will explain the up-coming deuterium experiment with these contents. (箇条書きを指しながら)
Finally, the report is summarized with my message.

4. high-performance regime
Significance of LHD in the world fusion research
High-performance steady-state plasmas is required to realize fusion reactor
LHD is based on Japan-originated heliotron concept
LHD has demonstrated its inherent advantage for steady-state operation
Duration: 47min.39sec
2keV, 1.2×1019m-3, 1.2MW, 3.36GJ
towards steady-state
high-performance regime
First of all, I would like to emphasize the significance of LHD in the world fusion research.
It is needless to say that high-performance steady-state plasmas is required to realize fusion reactor. LHD is based on Japan-originated heliotron concept, and has demonstrated its inherent advantages for steady-sate operation.
Here shown left is the progress of steady-state operation in LHD. LHD has demonstrated almost 48 minutes-long discharge with a few keV range, achieving the world record of the total injected energy, 3.36 GJ. As shown in the right figure, LHD has explored a long-pulse operation regime. In helical systems, the improvement of the plasma performance is required while tokamaks should achieve steady-state operation keeping high plasma performance.
Complementary research towards realization of high-performance and steady-state are highly necessary, for which the IEA SSOCG, steady-state operation coordination group, has played active roles worldwide. The NIFS has co-chaired this activity. 　(っ国際枠組みでの貢献を強調：武藤先生がCo-chair、委員:久保さん)
Co-chair
Co-chair of IEA SSOCG (Steady-state Operation Coordination Group)

5. MHD in current-free plasmas Dynamic wall retention
Progress towards high-performance plasmas
Steady increase of plasma parameters in recent years
Coming deuterium experiment should further extend the parameters towards reactor-relevant regime, in which advanced research can be performed for establishing firm basis for steady-state helical reactor
Parameters
Achieved
Key physics
Target Ti
8.1 keV (ne = 11019 m-3)
Ion ITB
Impurity hole
10 keV
(ne = 21019m-3) Te
20 keV (21018 m-3)
10 keV (1.61019 m-3)
Electron ITB
(21019m-3)
Density
1.21021m-3 (Te = 0.25 keV)
Super dense core
41020 m-3
(Te = 1.3 keV) 
5.1 % (BT = T)
4.1 % (1 T)
MHD in current-free plasmas
5 %　
(BT = T)
Steady-state
operation
54min. 28sec
(0.5MW, 1keV, 41018m-3)
47min. 39sec.
(1.2MW, 2keV, 11019m-3)　
Dynamic wall retention
1 hour
(3 MW)
Progress towards high-performance plasmas have also been made recent years in LHD. Key plasma parameters, such as temperature, density and beta values, have been progressing, also accompanied with physics findings and increased understandings.
Up-coming deuterium experiment should further extend the parameters towards reactor-relevant regime, in which advanced research can be performed for establishing firm basis for designing steady-state helical fusion reactor.

6. Extension of temperature regime
Plasma control and physics findings extended temperature regime
Ti had been extended above 8 keV (ion ITB)
ICH/ECH wall conditioning
Feedback ECH optimization in high-Ti plasmas
 Extended temperature regime to high Ti and Te, simultaneously reaching around 6 and 8 keV, respectively.
In the following three pages, I would like to briefly touch on the progress of LHD experiment.
The first topic is the extension of the operational space in plasma temperature.
Ion temperature had been pushed above 8 keV (最も右側の青点指示). ICH/ECH wall conditioning has been effective to reduce recycling, to enhance NB penetration to the core region. We have also made efforts to raise the ion and electron temperature simultaneously with increased ECH power, and the feedback ECH optimization for fine-tuned ECH is superposed onto the high-Ti plasmas. This has successfully extended the temperature regime in the direction of comparable Ti and Te, reaching around 6 and 8 keV, respectively. (赤丸：右側にある２点の辺り指示)
H.Takahashi et al., PPC/1-1, IAEA-FEC (2016)

7. High-beta plasma production
High beta has been realized with two scenarios in LHD
Ap = 5.8
(~2003)
Ap = 6.3
(2004)
Ap = 6.6
(2005~)
Standard Scenario
SDC Scenario
Sawtooth
Collapse
Standard scenario (broad P-profile)
- Low Ap configuration to increase heating efficiency, and to optimize transport, MHD
- Central  ~ 10 %, <> of 5.1 %
SDC (Super Dense Core) scenario (peaked P-profile)
- Peaked P profile by multiple pellet injections
- High density (> 1020 m-3)
As for the high-beta plasma production, we have intensively explored wide-ranging magnetic configurations for current-free, that is, disruption-free plasmas.
There have been two scenarios for high-beta plasma production, one is so-called standard scenario based on broad pressure profile, and the other is based on the discovery of so-called SDC (super dense core) with peaked pressure profile. Volume-averaged beta of 5.1 % has been achieved in the standard scenario.
(低衝突周波数領域での研究展開については割愛)

8. Particle balance in steady-state plasmas
Divertor plates
deposition layer on first wall
Time
He retention
total wall retention
Wall does not saturate during 48 min. discharge due to deposition layers
Dynamic change of He retention
Three different retention phases:
1. quite high wall pumping
by implantation in divertor plates
2. inventory declination
by out gassing due to increased surface temperature of divertor tiles
3. continuous wall pumping
by deposition layer on the first wall
can be explained by the global particle balance and plasma-exposed sample analyses.
Deposition layers continuously grows during the long-pulse discharge.
Next, I will tell you the progress on particle balance study during in steady-state plasmas.
This figure shows the time trace of the 48-minutes long-pulse helium discharge. (図Cを指して）This red dashed curve indicates the wall inventory of helium. From this curve, we can see the dynamic change of the helium retention. Three different retention phases are recognized. Phase one is …（箇条書きを読む）…, and phase three is …
This dynamic change of the helium retention can be explained（ポンチ絵を指しながら、箇条書きの下を読む）…
The deposition layer continuously grows during the long-pulse discharge, and that’s why the wall does not saturate during 48-min. discharge.
We have accumulated and advanced understandings on particle balance issues in steady-state plasmas by fully exploiting the world-leading steady-state plasma platform.
G.Motojima et al., EX/P8-3, IAEA-FEC (2016)

9. Objectives of LHD deuterium experiment
High-performance plasmas through confinement improvement
Scientific research in more reactor-relevant conditions
Full of research opportunities
Clarification of the isotope effect on confinement
Long-standing mystery in world fusion research
Needs to be understood towards burning plasma
Demonstration of the confinement capability of energetic ions in helical systems
Perspectives towards helical reactor
Isotope effect on PWI
Global particle balance for hydrogen isotopes
Now, let me move on to explain the LHD deuterium experiment that will start from next March.
Here are the main objectives we have listed up for the deuterium experiment.
Firstly, high-performance plasmas through confinement improvement for promoting scientific research in more reactor-relevant conditions. Full of research opportunities should be provided.
Secondly, clarification of the isotope effect on confinement. The isotope effect is the long-standing mystery in world fusion research. Physics understanding is crucially important towards accurately predicting behavior of burning plasmas.
Thirdly, the demonstration of the confinement capability of energetic ions. This is also a crucial issue to be clarified towards helical reactor.
Finally, I would like to point out the importance of PWI study in deuterium plasma. Global particle balance for hydrogen isotopes should be clarified with the installed tritium recovery system.

10. Schedule for LHD deuterium experiment
Concluded the agreements for LHD deuterium experiment with local governments in 2013
Deuterium experiment will start in March 2017 and will last 9 years
Preliminary Experiments for Commissioning
Calibration Experiments for Neutron Diagnostics
2016
Upgrade for Diagnostics System
(Neutron diagnostics, etc.)
Installation of Safety Equipments
(Tritium removal system, etc.)
Remodeling of Building and Facilities
Upgrade for Heating System
(NBI, ECH, ICRF)
Agreements for D-exp.
Deuterium Experiments
Legal License
Hydrogen Experiments
Preparation for D-experiment
Deuterium Experiments (9 years)
NBI: 18MW (60-80keV, 2sec)
14MW (180keV, 2sec)
ECH: 6MW-3sec, 1MW-CW
(77GHz & 154GHz)
ICRF: 6MW-5sec, 2-3MW-CW
Closed Helical Divertor with Pumping System
Neutron Diagnostics
High-energy Particle Measurement
3-Dimensional Measurement
High-Accuracy Measurement
Divertor Diagnostics
Steady-State Data Acquisition
PWI Laboratory
Ti = 10keV
at 21019 m-3
Target
in D-Exp.
<β> ~ 5%
at Bt=1T
nT
　>11020
m-3 keV s
3MW Heating
for 1 hour
2013
This is the schedule of the LHD deuterium experiment.
After the conclusion of agreement for the deuterium experiment with local governments in 2013, we have been preparing these things, and now almost completed(, and are ready to start).
So, the deuterium experiment is scheduled to start in next March, and will last 9 years.
The target parameters are summarized here.

11. Upgrades of facilities for deuterium experiment
Tritium Removal System
Integrated Radiation Monitoring System
Monitor
Upgrade of Diagnostics　( Neutron Diagnostics, etc)
Control System
Remote Control
Monitor
Monitor
Monitor
Monitor
Stack
Upgrade of NBI, ECH and ICH
ＬＨＤ
Here are schematics of major upgrades of facilities for safe and productive deuterium experiment.
For the radiation safety, tritium removal system, integrated radiation monitoring system and access control system have been ready.
As for increasing the cutting-edge capabilities of deuterium experiment, diagnostics, heating and closed helical divertor have been upgraded or newly installed.
Closed Helical Divertor
Access Control System

12. World-leading negative-ion-based NBIs
Negative-NBIs reliably inject 15MW of 180keV- H-beams into LHD plasma.
For D-beam injection, upgrade of the negative ion source performance with understanding of the source physics is being carried out.
Such engineering and physics research should contribute to ITER-NBI development.
High current of >30A (per source) is available PG GG EG Z Y
Source plasma
Beam
Negative-ion flow near PG 14 24 16 18 22 20 2 4 6 8 10
Y [mm]
Negative-ion rich plasma (nH->>ne) is produced near PG.
Negative-ion flow in the source plasma is evaluated for the first time.
Let me emphasize one of the upgrades here.
The upgrade of NBI system has been executed for the deuterium experiment. The powerful NBIs are main heating systems in LHD, and have much contributed to the extension of the plasma parameter regime and the physics research.
Especially, negative-NBIs reliably inject 15MW of H-beams with the energy of 180keV, which have been the world leading negative-NBIs.
For the deuterium experiment, upgrade of the negative ion source performance has been carried out along with the research of the beam-source physics. Recently, negative-ion rich plasma, consisting of positive and negative ions with an extremely small amount of electrons, is produced, and negative-ion flow in the source plasma is evaluated for the first time.
Such engineering and physics research should also contribute to ITER-NBI development.
Z [mm]
M.Kisaki et al., FIP/1-4, IAEA-FEC (2016)

13. In-situ neutron flux monitor (NFM) calibration
235U fission chamber(FC),10B counter and 3He proportional counter
Neutron source：252Cf (800MBq,108n/s)
Train
Sn (n/s) = α×Crate (cps): α should be obtained
Black line in graph FC
10B counter
As the final phase of the preparation for starting the deuterium experiment, we just conducted the In-situ neutron flux monitor calibration in November. The calibration was carried out along the guideline discussed in the workshop on the neutron calibration in 1989 at PPPL.
The neutron flux monitor consist of three U-235 fission chambers, B-10 counter and two He-3 proportional counters is installed for measuring total neutron emission rate and amount. From November 7th to 18th, 2016 we performed a in situ calibration of neutron flux monitor by means of californium-252 which intensity of 800 M Bq and train track system. Typical time evolution of pulse counts of He-3 and B-10 detector are shown. The period of pulse counts of 3-He detector around 40 s is the same as that of the train rotation. The pulse counts of B-10 detector shows almost constant because the detector located on the center position of LHD. FC
10B counter
3He proportional counter

14. LHD International Program Committee (LHD_IPC)
Alphabetic order
X. Duan (SWIP)
P. Gohil (GA)
C. Hidalgo (CIEMAT)
W. Heidbrink (UC Irvine)
L. Hu (ASIPP)
H.K. Park (NFRI)
B. Pégourié (CEA/IRFM)
Maria-Ester Puiatti (RFX)
U. Stroth (IPP-Garching)
R. Wolf (IPP-Greifswald)
M. Zarnstorff (PPPL)
[ term: three campaigns, reappointment possible]
[ LHD experiment board members ]
T. Morisaki (Executive director on science)
M. Osakabe (Executive director on device)
S. Kubo (Division director: plasma heating physics)
S. Sakakibara (Division director: high-temperature plasma physics)
Theme group leaders (FY campaign)
M. Yokoyama
K. Nagasaki (Kyoto U.)
R. Sakamoto
M. Sakamoto (Tsukuba U.)
K.Y. Watanabe
S. Inagaki (Kyushu U.)
To further strengthen the international collaboration and the usage of LHD deuterium experiments opportunities, we have set up the LHD international program committee (LHD_IPC).
The committee consist of distinguished foreign colleagues (from China, France, Germany, Italy, Korea and USA), and LHD experiment board and theme group leaders.
The committee members, in particular, foreign colleagues, are expected to give advise to LHD deuterium experiment, to act as a key person in each institution or topic to facilitate the collaboration. We held the kick-off meeting during IAEA-FEC on October.
(FPA参加者への呼びかけの意味で)
Also, we will be planning to hold the LHD deuterium workshop (probably) every year. Please participate and contribute to it, to fully exploit the experiment opportunities and capabilities.

15. Helical reactor (FFHR-d1) design and R&D
1. Construction/maintenance scenario
2. Development of new materials
Low activation vanadium alloys
High strength
NIFS-HEAT-2 ingot
(166 kg)
High temperature
& long life
Advanced Cu alloy for divertor
Mechanical Alloying and Hot Isostatic Press
High strength
3. Integrated blanket system study by circulation loops
Alloying
time
Smaller grain size
Based on all the knowledge and experiences obtained and envisaged in the LHD experiment, wide-ranging R&Ds for fusion engineering issues are executed towards the helical fusion reactor, such as 1.---, 2.---, 3.---, and These results have been integrated into the design of helical fusion reactor, named as FFHR-d1.
The details of the entire activity and individual progress are reported in several presentations in this conference.
4. Divertor mock-up and heat load tests
High heat flux test facility
Oroshhi‐2: Operational Recovery Of Separated Hydrogen and Heat Inquiry-2

16. Summary
LHD has progressed as a large-scale superconducting device since 1998, without any severe cryogenic troubles
Demonstration of steady-state operation as inherent advantage of helical systems
Improvement of plasma performance based on extended experimental capabilities and physics findings
Deuterium experiment will soon start at next March
Further plasma performance improvement is envisaged in the coming deuterium experiment, to provide firm basis for helical reactor design
Now, let me summarize my talk.
LHD has progressed as a large-scale superconducting device since 1998, without any severe cryogenic troubles.
Steady-state operation has been demonstrated as inherent advantage of helical systems.
Plasma performance has been also improved based on extended experimental capabilities and physics findings.
Deuterium experiment will soon start at next March.
Further plasma performance improvement is envisaged in the coming deuterium experiment, to provide firm basis for helical reactor design.

17. Join us for the coming deuterium experiment !
Finally, now is the right time to convey a message to you all, “Join us for the coming deuterium experiment.”
We are pretty much looking forward to having your active participation, to enjoy full of challenges and discoveries together.
Thank you very much for your attention. .
Join us for the coming deuterium experiment !