(SG2, TC) Session Report

June 04, 2024 (H. Nakano)

Date: June 04, 2024
Time: 10:30 – 16:45
Shot#: 192502 – 192606(shots)
Prior wall conditioning: H2
Divertor pump: On
Gas puff: H2, He, Ar
Pellet: TESPEL(Ti)
NBI#(1, 2, 3, 4, 5) = gas(H, H, H, H, H)=P(4.7, 4.1, 4.2, 3.6, 3.0) MW
ECH(77GHz) = ant(1.5-Uo, 5.5-U, 2-OUR)=P(0.36, 0.70, 0.38) MW
ECH(154GHz) = ant(2-OLL, 2-OUL, 2-OLR)=P(0.71, 0.81, 0.98) MW
ICH(3.5U, 3.5L, 4.5U, 4.5L) = P(-, -, -, -) MWTopics
1. Interaction of EGAM, the turbulence and the radial transport (Akihiro Shimizu)
2. Turbulence response at both L-H and H-L transition (Tokihiko Tokuzawa)
3. Confinement study between dimensionally similar H and He plasmas in LHD (Naoki Tamura)
4. Effect of a mixed-ion plasma on impurity transport in NBI heated plasmas (Naoki Tamura)Interaction of EGAM, the turbulence and the radial transport(A. Shimizu, M. Nishiura, T. Ido(Kyushu Univ.))
Shot #: 192500 - 192529
Experimental conditions: (Rax, Polarity, Bt, g, Bq) = (3.75 m, CW, 1.375 T, 1.2538, 100 %)Motivation and objective: To investigate interaction between EGAM and turbulence by HIBPResults:#19252

6

Ø We tried to measure potential fluctuation of EGAM by HIBP, and to investigate
interaction between EGAM oscillation and turbulence.
Ø ECCD to co-direction was applied to control the rotational transform.
Ø Fluctuation signal of EGAM was measured by magnetic probe.
Ø Ion source of HIBP had troubles, so data of HIBP was not be obtained.

#192526
Magnetic probesignal
RSAE(Decrease Frq.)

This is n=1 mode

EGAM
Chirp upECCDIn HIBP, EGAM signal
is expected.

Turbulence response at L-H and H-L transitions (T. Tokuzawa)
Experimental conditions: (Rax, Polarity, Bt, γ, Bq)= (3.55 m, CW, 1.0 T, 1.2538, 100.0%) #192530 - #192562
Aim:• To investigate the response of turbulence during theLH transition. In particular, we aim to observe how
different scales of turbulence respond at the samelocation.
Results:• The L-H transition was successfully observed inHahydrogen gas. (The transition density is slightly higher
than that of D-exp).
• DBS (measured k^ ~ 7.5 cm-1) and BS (measured k ~ 30 Low-kcm-1) were able to observe the respective turbulence Turbulence
intensity
at approximately the same location.
• Exactly opposite responses were observed during theLH transition for low and high wavenumbers.
High-kTurbulence at low wavenumbers decreased inTurbulence
intensity with the LH transition, while turbulence at
intensity
high wavenumbers increased.

neTer~1.1
r~0.9
r~0.9
r~0.9

neConfinement study between dimensionally similar H and He plasmas in LHD (N. Tamura et al. )Experimental conditions: (Rax, Polarity, Bt, γ, Bq) = (3.60 m, CW, 2.75 T, 1.2538, 100.0%)
Shots: #192563 - #192586 (#192563 - #192565: NBI calib.)
Goal of this experimentl Characterize pure He plasmas with different heating conditions and compare their confinement properties with those in pureH plasmas in LHD
Resultsl We produced plasmas heated by ECH and by ECH+H-NBI
with a H gas-puff, following the He plasma experiments onMay 24
l Plasma profiles (ne, nHe, nH, Ti, Er, etc.) and fluctuations
obtained will be analyzed
ü Ar gas-puff was performed for the intrinsic impurity transportanalysis
ü Li2TiO3-TESPELs were injected for the tracer impurity
transport analysis

l In H-riched plasmas, the plasma
with ne_bar = 4e19 m-3 collapsed after
the TESPEL injection
ü Due to impurity accumulation?
ü A clear difference was also
observed with the TESPEL
between H and He plasmas
Y. Nakamura+,
NME 12(2017)124.

TypicalResult
TypicalResultininH-plasmaH-plasma(June 4)

Typical Result in He-plasma (May 24)

Effect of a mixed-ion plasma on impurity transport in NBI heated plasmas (N. Tamura, A. Dinklage et al. )Experimental Configuration: (Rax, Polarity, Bt, γ, Bq) = (3.9 m, CW, 2.5385 T, 1.2538, 100.0%)
Shots: #192587 – #192606 (#192587: NBI calib.)
Goal of this experiment: To study the change of the impurity accumulation window in H/D/He-mixed plasmas
Results:l We tried to change the He contents in the plasma by using different gas puffsettings around ne_bar of ~4e19 m-3
l When He contents increased, the plasma duration was prolonged, and Bolometersignal level was decreased
ü To study impurity transport, Ar gas was puffed at t = 3.450 s and Ti-TESPEL wasinjected at t = 4.27 s
ü Ar line emission intensity level, and Ti line emission intensity level will be checkedlater
l Finally, we obtained a good data set of the D/(H+D) = (0.0, 0.2, 0.5, 0.9)
with Rax = 3.9 m
ü We have also similar data set with Rax = 3.6 m
ne(e19 m )w/ He-puff
ü A detailed comparison between Rax = 3.6 m and Rax = 3.9 m will be donel Ar He/Li-like profile measured with CXS and Er data will be analyzed later-3

ne(e19 m-3)
w/o He-puff

Black dashed lines showref. data (w/o He-puff)

heating
w/ He-puff
heating
w/o He-puff(H+D)/(H+D+He)

nebar (e19 m-3)

Prad(MW)