(IA) Instability and Anisotropy group report
Date: Mar. 22, 2024
Time: 14:45 - 16:45
Shot#: 188094 –188133 ( 40 shots)Mar. 26, 2024 (R. Seki)

Prior wall conditioning: OFF
Divertor pump: off
Gas puff: H2, Pellet: H
NBI#(1, 2, 3, 4, 5)=gas(H, H, H, H, H)=P(--,--,2.0,3.6, 5.6)MWECH(56GHz)=ant(1.5-U)=P(-.-)MW
ECH(77GHz)=ant(5.5-U, 2-OUR)=P(0.698, 0.38)MWECH(154GHz)=ant(2-OLL, 2-OUL, 2O-LR)=P(0.389, 0.806, --)MWICH(3.5U, 3.5L, 4.5U, 4.5L) = P(0, 0, 0, 0)MWTopics
1. Investigation of the impact of the fast-ion losses (FI) induced by pellet injection on the density limit in LHD
plasmas. (B.L.Miranda, N. Panadero)

125th Experimental campaign – report 22/march session

Investigation of the impact of the fast-ion(FI) losses induced during pellet injection
on the density limit (DL) in LHD plasmas
Belén López-Miranda (CIEMAT),
Naoki Tamura (NIFS), Rayosuke Seky (NIFS), Kieran J. McCarthy(CIEMAT), Nerea Panadero (CIEMAT)

belen.lopez.miranda@ciemat.es2024/03/26

Report session 22/march - B. López-Miranda
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LHD Research Forum B. López-Miranda (CIEMAT) 2024/03/26

Objectives and expected results▪ Objectives: Stellarator plasmas can suffer from confinement
degradation and radiative collapse leading to their prematuretermination. Plasma performance can be aggravated by the prematureloss of high-energy ions. Recently, in the TJ-II, it has been observed,
using the FILD, that FI losses are significantly reduced by cryogenic
PIs in NBI heating plasmas. This may indicate that PI plays anadditional role in improving plasma performance, as well as modifying
the radial density profile, and might a role in the DL.
▪ This experiment aims to study the impact of FI population and AE
induced during the injection of cryogenic pellets on the density limit inthe LHD.
2024/03/26

Report session 22/march - B. López-Miranda

3Approach & methodology▪ Session planning/shot sequence:▪ 40 discharges▪ Rax = 3.6 configuration▪ Pellet at maximum energy → Characterize the effect on FI▪ Shots: 188096 - 188133
Heating power I (1nNBI (#3) 2pNBI (#4, #5))

3.8 mm
3.4 mm3 mm

Heating power II (1nNBI (#3) 1pNBI (#4))

3 ·1019 m-3

4 ·1019 m-3

5 ·1019 m-3

3 ·1019 m-3

4 ·1019 m-3

5 ·1019 m-3

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2024/03/26

Report session 22/march - B. López-Miranda

4240322_LHDxp_SG3_BLM_Experiment
NBI

Pellet size Number of discharges

Scenario I:x

188099-100: References

Heating I, 3 x
1019

3.8 mm188101-102

3.4 mm188103-104

Scenario II:x

188105-106: References

Heating I, 4 x
1019

3.8 mm188107-108

Scenario III:x

188110: Reference

Heating I, 5 x
1019

3.8 mm1881092024/03/26

Report session 22/march - B. López-Miranda

5240322_LHDxp_SG3_BLM_Experiment
Scenario I: 3.8 mm #188101

2024/03/26

Scenario II: 3.8 mm #188107

Report session 22/march - B. López-Miranda

Scenario III: 3.8 mm#1881096

240322_LHDxp_SG3_BLM_Experiment
NBI

Pellet size Number of discharges

Scenario I.2:

x188115: References

Heating II, 3 x
1019

3.8 mm188116-117

3.4 mm188119-122Scenario II.2:x

188123-124: References

Heating II, 4 x
1019

3.8 mm188125-126

3.4 mm188127-128

Scenario III.2:x

188129-130: Reference

Heating II, 5 x
1019

3.4 mm1881312024/03/26

Report session 22/march - B. López-Miranda

7240322_LHDxp_SG3_BLM_Experiment
Scenario I.2: 3.4 mm #188119

2024/03/26

Scenario II.23.4 mm #188128

Report session 22/march - B. López-Miranda

Scenario III.2: 3.4 mm #188131

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Thank you for your attention

2024/03/26

Report session 22/march - B. López-Miranda

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