(SG1) Multi-phase and Atomic/Molecular physics group report
May 14, 2024 (M. Kobayashi)
Date: May 10, 2024
Time: 10:30 -16:45
Shot#: 190927 – 191046 (120 shots)
Prior wall conditioning: No
Divertor pump: Off
Gas puff: H2, N2, Ne, Ar IPD: No
LID: 3000A
NBI#(1, 2, 3, 4, 5)=gas(H, H, H, H, H)=P(4.4, 3.9, 4.4, 3.4, 4.1) MW
ECH(77GHz)=ant(5.5-U, 2-OUR)=P(698, 380)kW
ECH(154GHz)=ant(2-OLL, 2-OUL, 2O-LR)=P(705, 889, 982) kW
ECH(116GHz)=ant(2O-LR)=P(-)kW
ECH(56GHz)=ant(1.5-U)=P(-)kW
ICH(3.5U, 3.5L, 4.5U, 4.5L) = P(-, -, -, -) MWTopics
1. Understanding of the evolution of cosmic organic dust in reaction with plasma (I. Sakon)
2. Electron temperature locking at edge magnetic island during detachment (M. Kobayashi)
1

20240510

Understanding of the evolution of cosmic organic dust in reaction with plasma(I. Sakon, T. Miyata, T. Onaka, K. Kobayashi, Y. Kebukawa, J. Takahashi, M. Tanaka, H. Nakamura, M. Shoji, S. Masuzaki, M. Kobayashi)
Background & objectives: In the previous run (Cycle 24 experiment), the experiment was conducted at the LHD of the NIFS, irradiating hydrocarbon dust with a relatively lowenergy plasma (hydrogen and nitrogen) at the outer edge of the LHD plasma. Preliminary analysis revealed changes in infrared properties of filmy QCC that reproduce thecharacteristics of peculiar unidentified infrared bands observed in galaxies with weak active galactic nuclei (Smith et al. 2007) and in elliptical galaxies (Bregman et al. 2008;
Kaneda et al. 2005), characterized by the absence of the 6-9μm bands corresponding to stretching modes of aromatic C-C bonds and the presence of only the 11-14μm bands
corresponding to out-of-plane bending modes of aromatic C-H bonds. While the polycyclic aromatic hydrocarbons (PAHs) hypothesis is widely accepted in astronomy as thecarrier of these bands, the exact understanding of their nature is incomplete. Thus, the identification of the carrier responsible for these bands and the determination of thephysical factors giving rise to their characteristics remain unresolved for galaxies with weak active galactic nuclei and elliptical galaxies. Here we propose exposure experiment ofhydrocarbon solids to the Large helical Device (LHD) plasma by means of a movable sample holder in the 10.5-L port and collect organic dust on the Si or SiO2 substrate.The
present study aims to understand the properties of interstellar organic matter in space, based on an integrated approach involving astronomical observations, experimental
astrophysics, and molecular dynamics simulations.
Reference:[1] J. D. Bregman et al. 2008, ASP Conf. Ser. 381, 34, [2] I. Endo, I. Sakon, T. Onaka et al. 2021, ApJ, 917, 103, [3] H. Kaneda et al. 2005, ApJ, 632, 83, [4] J. D. T. Smith et al. 2007, ApJ, 656, 770

Results:
10mg of Coronene C24H12 on a SiO2 substrate (x1) and a few mg of filmy QCC on a Si substrate (x2)
are exposed to the Hydrogen and nitrogen plasma (low-energy part of the LHD plasma). N2 aresupplied at 3.5L port and 5.5L port. Experiment parameters of each shot are given in the following table.
The probe to monitor the properties of plasma was attached to the sample holder and we confirmed thatreaction with plasma flow of *** was achieved for each shot.

Shot ID

N2 (5.5L) N2 (3.5L)

1909401500msec 200msec-300mm190941

1500msec 200msec-200mm190942

1500msec 200msec-150mm1909431500msec 200msec-100mm190944

1500msec 200msec-100mm, collapse

190945None-100mmNone

H (5.5L)

comment2Experiment on LHD (cycle 25)
at National Institute for Fusion Science
C24H12 on SiO2 substrate
0.5coronene(20240425)

ATR; absorbance

0.4?

0.3
0.2
0.102345678910111213141516

wavelength (um)Filmy QCC #1 on substrate
0.03

Filmy-QCC(20240425)

ATR; absorbance

0.025
0.02?

0.015
0.010.005
02345678910

111213141516

wavelength (um)Filmy QCC #2 on substrate
ATR; absorbance

0.02

Filmy-QCC#2(20240425)

0.015

?

0.010.005

023

45678910

wavelength (um)111213141516

Electron temperature locking at edge magnetic island during detachment
M. Kobayashi, 20240510
Motivation & Objectives:
It has been observed that the electron temperature at the island is “fixed” (Te locking) to a constant value during Neon seeding experiments while theradiated power increases according to the impurity seeding amount. In the present experiments, Ar seeding was conducted to investigate the impact ofdifferent cooling function on the Te locking.
Results:
Rax = 3.85m, B=2.57T, CCW, γ=1.254, Bq=100%. ECH ~3MW.

Ar seeding

Ar seeding: Te at the island is fixed to ~140eV during Ar
seeding scan, while radiated power increases. More than
32 ms Ar pulse led to radiative collapse.

VUV spectra weremeasured.

Inboard island

Te [keV]To sustain Ar seeding
plasma, more power isneeded.
Prad estimate:~ 3 MW with Ne at 30eV,~13 MW with Ar at 10eV,
which is beyond ECHpower.

Ar puff

ne [1016 m-3]

Ne seeding: Te is fixed to ~140eV or ~30eVduring Ne
seeding scan. Te changes stepwise and no intermediate
values are possible. This suggests that the system isbistable. After the transition to lower Te (30eV) the radiationis almost doubled.

Ar pulse:
10 ms
20 ms
32 ms

Ne seeding

Ne puff
Outboard island

No intermediate
values possible

Ne pulse:
10 ms
20 ms
26 ms