(SG2, TC) Session Report
Date: April 2, 2024
Time: 10:30 – 16:45
Shot#: 188625 – 188747 (123 shots)
Prior wall conditioning: None
Divertor pump: On
Gas puff: H2, Ar
Pellet: Carbon pellet
NBI#(1, 2, 3, 4, 5) = gas(H, H, H, H, H)=P(2.4, 2.4, 2.3, 3.8, 5.4) MW
ECH(77GHz) = ant(1.5-Uo, 5.5-U, 2-OUR)=P(0.44, 0.38, 0.7) MW
ECH(154GHz) = ant(2-OLL, 2-OUL, 2-OLR)=P(0.8, 0.98, -) MWICH(3.5U, 3.5L, 4.5U, 4.5L) = P(-, -, -, -) MWTopics
1. Core and edge turbulence in modulated ECH( M.Nishiura)
2. Turbulence characteristics in density-peaking plasma in LHD (R.Yanai)
3. Comparison of turbulence driven transport between LHD and W7-X (H.Sakai)

April 3, 2024 (M.Yoshinuma)

Core and edge turbulence in modulated ECH

M. Nishiura, R. Yanai, A. Shimizu, et al.

LHD experiment summary on 2 April 2024
PurposeThe feature of density peaking on energetic ion anisotropy isevaluated by using an EC heating to change a neoclassical /turbulence transport.
Result• The density peaking is observed at 1x1019m-3, 1.5x1019m-3,
and 2x1019m-3. When the density is increased, the peaking
becomes large.
• Modulated ECH(MECH) is applied at r/a=0, 0.5, and 0.9 to thedensity peaked plasmas to analyze a heat and particle
transport. The heat transport is analyzed by Yanai. The
particle transport is evaluated by MECH to change in thepeaked density profiles.
• HIBP measures the electric potential.
• Doppler back scattering (DBS) will be analyzed.
• The modeling of this situation will be validated by FORTEC-3Dand GKV.

TeneMECH

Turbulence characteristics in density-peaking plasma in LHD (R. Yanai et al. )Experimental conditions: (Rax, Polarity, Bt, γ, Bq) = (3.60 m, CW, 2.75 T, 1.2538, 100.0%)
Goal of this experiment:• Investigating the characteristics ofturbulence in density-peaking
plasma in LHD.
Results:• Density peaking plasma wassustained by perpendicular NBIs
and tangential NBIs were injectedfrom 4 sec.
• By tangential NBIs, Te increased,and density peaking slightly
decreased.
• In PCI data, the density
fluctuations in 30-150 kHz
decreased, and that in 3-30 kHz
increased by injecting tangential
NBIs.
• BS data was also measured andwill be analyzed.

t=4 sec
t=4.7 sec

NBI, ECH

𝑛 , Wp

PCI 3-30 kHz
30-150 kHz
150-500 kHz
Tene

Comparison of turbulence driven transport between LHD and W7-X (H-case)
H. Sakai (Kyushu Univ.), K. Tanaka
Shot No: #188713~188747 (35 shots)Experimental conditions: (Rax, Polarity, Bt, γ, Bq) = (3.6 m, CW, 2.75 T, 1.2538, 100 %)Gas-puff: H2Approach
To clarify more detail difference in the picture of turbulence driven transport in LHD and W7X, electron density scan was performed as flat-top with ECH (2,3MW). In addition, tounderstand more detail for Ti stiffness in LHD, NB power scan was also performed with flattop fixed density (aimed to 1.5x). Latter was optional experiment.
Phase1 (ECH) Phase2 (NBI) Phase3 (NBI)
Density scanPower scan
0.5-5.0x
1.1-9.8MW

Phase1
Phase2

3.3 3.6

5.0

5.6

7.6

9.0

9.6Results On ECH phase, good flat-top plasmas were obtained. While this timing, sweeping detector PCI (which was developedfor W7-X) was running, which enables to compare the results from same measurement method.
 On NBI phase, the experiment was partially successful. Unfortunately, flat-top density could not be obtained especiallywith BL5. However, time evolution of ion-scale turbulence should be obtained because conventional 2D-PCI wasworking. Therefore, we will choice suitable timing for evaluating Ti stiffness.

Phase3