(IA) Instability and Anisotropy group report
Date: Apr. 16, 2024
Time: 10:30 - 12:15, 13:30-16:45
Shot#: 189571 –189601, 189622-189668 (78 shots)
Prior wall conditioning: He(Sat. and Sun.)
Divertor pump: off
Gas puff: He, H2, Pellet: no
NBI#(1, 2, 3, 4, 5)=gas(H, H, H, H, H)=P(4.6,3.9,4.3,4.9,5.4)MWECH(56GHz)=ant(1.5-U)=P(-.-)MW
ECH(77GHz)=ant(5.5-U, 2-OUR)=P(0.109, 0.112)MWECH(154GHz)=ant(2-OLL, 2-OUL, 2O-LR)=P(0.145, 0.143, 0.11)MWICH(3.5U, 3.5L, 4.5U, 4.5L) = P(0.65, 0.5, 0.67, 0.58)MWApr. 17, 2024 (R. Seki)

Topics
1. Investigation of instability driven by ICRF fast ion. (R. Seki and J. Wang)
2. Understanding the dependence of fast ion distribution on various magnetic
field configurations using the newly installed Imaging Neutral Particle Analyzer (INPA) (S.
Sangaroon, K. Ogawa)1

Investigation of instability driven by ICRF fast ion.(R. Seki and J. Wang.)
Shot #:189571 –189601, 189642-189668

SN 189662

SN 189664

Experimental conditions: (Rax, Polarity, Bt, γ, Bq) =(3.6, CW, 2.5, 1.2538, 100), (3.6, CW, 2.75, 1.2538,100) (3.6, CW, 1.25, 1.2538, 100)

neBackground and motivation:• The ICRF fast ion kick model was introduced tothe MEGA for analyses of the instability induced dueto the ICRF fast ion. In the MEGA simulation, the fastion induced instabilities are destabilized in the case of～ 2.5 T, where the ICRF resonance layers are set
near the magnetic axis.
Results:• Since it was not possible to start up the plasma
only with three ECHs, we observed the fast-ion
distribution and magnetic fluctuation in the case of
2.75 T and 1.25 T.
• The instabilities which may be driven by ICRF fastions could be observed.
• We will validate the MEGA simulation bycomparing magnetic fluctuation and fast-ion tailwith DNPA.

Ip~
bq~
bq

Fig.1 Time evolution of ICRF and ECH power, density,
signal of magnetic probe.

Understanding the dependence of fast ion distribution on various magnetic field
configurations using the newly installed Imaging Neutral Particle Analyzer (INPA)S. Sangaroon (MSU), K. Ogawa (NIFS), M. Isobe (NIFS), W. Paenthong (SOKENDAI), X.D. Du (GA),
A. Wisitsorasak (KMUTT), N. Poolyarat (TINT), B. Chatthong (PSU), T. Onjun (TINT)

3.6 m, CW, 2.75 T

Experimental conditions: (Rax, Polarity, Bt, γ, Bq) =(3.9 m, CW, 2.538 T, 1.2538, 100.0%) Shots: #189628 - #189640*On 29 March 2024, we have: 3.6 m, CW, 2.75 T for density scan.
Motivation & Objectives• We newly installed INPA as part of acollaboration between Japan, Thailand, and theUS to gain a deeper understanding of energetic
particle behavior in the helical device.
• This proposal aims to analyze the fast ion
distribution within LHD plasma encompassing avariety of magnetic field configurations utilizing
the INPA, including: variations in magnetic fieldstrengths (Bt ), variations in the magnetic axis(Rax), variations in the plasma density (ne)2 x 1019 m-3

1 x 1019 m-3

3.9 m, CW, 2.538 T

0.5 x 1019 m-3

1 x 1019 m-3

1.5 x 1019 m-3

2 x 1019 m-3

3.5 x 1019 m-3

4 x 1019 m-3

Results• With this configuration, we successfully
observed a scintillation spot correlated withperpendicular neutral beam (P-NB) injection withthe density scan between 0.5 - 4 x 1019 m-3.
• We will investigate the effect with magnetic axis(Rax) of 3.6 m, 3.75 m in CCW.

2.5 x 1019 m-3

3 x 1019 m-3