(MAP) Session Report
Date: Apr. 23, 2024
Time: 10:28 – 16:43
Shot#: 190009 – 190121 (113 shots)
Prior wall conditioning: H2 GDC (4/20, 4/21)
Divertor pump: Off
Gas puff: H2, Ar

Apr. 24, 2024 (R. Yanai)

Pellet: B, W
LID: On

NBI#(1, 2, 3, 4, 5) = gas(H, H, H, H, H)=P(4.7, 4.1, 4.2, 3.1, 3.2) MW
ECH(77GHz) = ant(1.5-Uo, 5.5-U, 2-OUR)=P(-, 0.698 0.38) MW
ECH(154GHz) = ant(2-OLL, 2-OUL, 2-OLR)=P(0.705, 0.889, 0.982) MWICH(3.5U, 3.5L, 4.5U, 4.5L) = P(-, -, -, -) MWTopics
1. Database construction of boron ion emission lines (M. Goto)
2. Effect of boron impurity powder injection on tungsten impurity transport in the LHD core plasma (T. Oishi(Tohoku Univ.))
3. Spectroscopic analysis of divertor detachment (M. Goto)
4. The sustainment of divertor detachment by injection of impurity dust particles into the magnetic island in theLHD peripheral plasma using the IPD (M. Shoji)Database construction of boron ion emission lines
M. Goto, K. Nojiri (QST) and T. Kawate

Experimental conditions:(Rax, Polarity, Bt, γ, Bq) = (3.6 m, CW, 2.75 T, 1.2538, 100.0%),(3.9 m, CW, 2.5385 T, 1.2538, 100.0%)#190029 - #190030, #190070-190089

Motivation and method:Ø ITER-DIM (Divertor Impurity Monitor) considers
to use Boron emission lines for plasma
parameter measurement.
Ø Boron IPD and pellets are used to accumulate
data for emission lines of boron ions.
Ø The composition of the pellets used in thisexperiment are examined.
Results:
Ø It was confirmed that spectrum for the pellet
ablation cloud mainly consist of boron ionemission lines.
Ø Localized line emissions of boron ions in thedivertor were observed with the boron IPD
discharge.

BII

Hα#190087
ablation cloudBII#190087

BIII

HαBII

divertor
BII
BI（？）

BII

23, 2024 T. Oishi (Tohoku Univ.)
Effect of boron impurity powder injection on tungsten impurity transport in the LHD core plasma Apr.
Caretaker: S. Masuzaki

Conditions: Rax = 3.6 m, Bt = 2.75 T, CW, g = 1.2538, Bq = 100.0 % #190034-190069 (total 36 shots)
Objective: A significant reduction of iron impurities has been observed when boron powders are injected by the impurity powder
dropper (IPD). -> Boron IPD has a potential to be an effective impurity control method. We aim to investigate the effects of boron IPD
on tungsten impurity transport in the core plasma of LHD.
Results:- For the discharges [w/ IPD, w/o IPD] x [ne = 1, 2, 3, 4 x 1013cm-3], spectroscopic date were obtained in the EUV, VUV, and visible
wavelength range.
- Although the discharge w/ IPD appears to have smaller line spectra of W41+-W45+ charge states, it is necessary to consider the effectof IPD including the comparison of different electron temperatures and low to medium charge states of W ions.
W pelletW pellet•••#190047 w/o IPD
W pellet @ 3.9 s
ne before pellet
injection ~ 4 x 1013cm-3IPD•••#190051 w/ IPD ~4-5 s
W pellet @ 3.9 s
ne before pellet
injection ~ 4 x 1013cm-3

W41+
W45+
W43+ W42+

W41+
W45+
W43+ W42+

Spectroscopic analysis of divertor detachmentM. Goto and M. Kobayashi

Experimental conditions:(Rax, Polarity, Bt, γ, Bq) = (3.9 m, CW, 2.538 T, 1.2538, 100%)
LID: 3000 A (6-O)#190070-#190089

Motivation and method:Ø The Balmer series spectrum shows typicalrecombining plasma characteristics whenplasma is detached due to strong hydrogengas puff.
Ø Spectrum for NBI plasma is compared withthat for ECH plasma on April 10.
Results:
Ø Spectra also suggest a formation of therecombining plasma for NBI plasmas.
Ø The recombining plasma formation takes
place at different regions for ECH and NBIplasmas.

#189289 (ECH)#190078 (NBI)The sustainment of divertor detachment by injection of impurity dust particles
into the magnetic island in the LHD peripheral plasma using the IPD(M. Shoji)

Experimental conditions:

Ablation image of Si powders(Rax, Polarity, Bt, γ, Bq) = (3.90 m, CW, 1.375 T, 1.2538, 100%), Shots: #190091 - #190121#190119
ILID=(6O, -1950 A), Shots: #190093 - #190110, ILID=(6O, -3300 A), Shots: #190113 - #190121 2.5-U
ECH: only for start-up, NBI: #1-5, IPD: Silicon (4-5 sec.)

Objective:
Triggering and sustaining divertor detachment were tried by enhancing the radiation power
induced by the injection of dust particles (silicon and boron) into a magnetic island in theLHD peripheral plasma, which is for assisting the divertor detachment using the IPD.

Experiment:
Silicon powders (higher Z) were dropped into the peripheral
plasma (magnetic island) by the impurity powder dropper (IPD) in
high density plasma discharges (ne 〜 6×1019 m-3) for a low
magnetic field (B=1.375 T). The powder drop rate was optimized
step by step. Powder injection into plasma discharges with an
expanded magnetic island (ILID=-3300 A) were also tried.

Results:
The detached state was achieved at the startup phase of the plasma
discharge (~3.5 s). The silicon powder injection contributed to theslight enhancement of the radiation power, which was quite
smaller than what was originally expected.

#190115

Without IPD (Si)With ILID (-3300A)

Si powders#190119

With IPD (Si)With ILID (-3300A)

nene

Prad

Prad
IPD (Si)

Iimp

Iimp
Time (s)Time (s)