Toroidal rotation in ECRH L-mode, I-phase and

H-mode on HL-2A tokamak

A.P. Sun, J.Q. Dong, X.Y. Han, C.H. Liu, J.Y. Cao, M. Huang,

Y.G. Li, X. L. Huang and J.M. Gao

Southwestern Institute of Physics, China

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Outline

Introduction

Charge eXchange Recombination Spectroscopy (CXRS) in HL-2A tokamak

Toroidal rotation in HL-2A experiments with co-NBI

Toroidal rotation in ECRH L-mode discharges

Toroidal rotation in H-mode discharges

Toroidal rotation in I-phase of H-mode discharges

Summary

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Introduction

• Plasma toroidal rotation plays a key role in regulating turbulence and has a beneficial

effect on energy confinement in fusion devices.

•The toroidal rotation is studied on HL-2A in recent co-current direction NBI

experiments and charge exchange recombination spectroscopy (CXRS) is used to

measure its velocity profiles.

• Three cases are analyzed in this work.

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Charge exchange recombination spectroscopy in HL-2A tokamak

It is in the midplace at the low magnetic field side It has 8-13 channels Its spacial resolution is 3-5cm Its time resolution is 20ms

CXRS system sketch

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NBI starts at 410ms, end at 900ms.

ECRH first stage start at 522ms, second stage start at 675ms,

the last stage start at 828ms.

Toroidal rotation in HL-2A experiments with co-NBI

Toroidal rotation in ECRH L-mode discharge

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ECRH power deposition

After ECRH starts, toroidal rotation velocity decreases in the core plasma and near ECRH deposition position.

Toroidal rotation velocity changes little far away from ECRH deposition position.

Toroidal rotation velocity distribution vs time

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Toroidal rotation velocity decreases

significantly in the core plasma and

near ECRH deposition position.

Toroidal rotation velocity distribution vs R

The discharge parameters is similar to those in shot 19959, NBI and ECRH

starting and ending time is the same.

Toroidal rotation in ECRH L-mode discharge

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After ECRH starts, toroidal rotation

velocity decreases in the core plasma and

near ECRH deposition position.

Toroidal rotation velocity decreases

significantly in the core plasma and near

ECRH deposition position.

Toroidal rotation velocity distribution vs time Toroidal rotation velocity distribution vs R

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Toroidal rotation in H-mode discharges

Time evolutions of the core and edge toroidal rotation

• The toroidal rotation velocities increase significantly from L-mode to H-mode discharges

• The direction of edge toroidal rotation is reversed at the L-H transition

• Both core and edge toroidal rotations decrease at the H-L back transition.

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Toroidal rotation profiles in H-mode discharges

The toroidal rotation continuously increases from L-mode to H-mode, and decreases from

H-mode to L-mode. However, it is higher in the L-mode phase after H-L transition than

that before the L-H transition.

The toroidal rotation profiles at different stages

The black line represents the L-mode phase.

The red line does L-H transition stage.

The blue line shows the beginning of the first

ELM.

The green line does H-mode phase.

The purple line shows H-L transition stage.

The yellow line represents back to L-mode

stage.

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Toroidal rotation in I-phase and H-phase of H-mode discharges

The toroidal rotation velocities are compared between I-phase and H-phase The stored energy increases from I-

phase to H-phase. The toroidal rotation velocities in I-phase are lower than those in H-phase.

The red square symbols represent I-phase the blue circular symbols do H-phase.

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Summary

In ECH discharges, after ECRH starts, toroidal rotation velocity decreases

significantly in the core plasma and near ECRH deposition position, and changes little

far away from ECRH deposition position.

In H-mode discharges, the toroidal rotation continuously increases from L-mode to

H-mode, and decreases from H-mode to L-mode. However, it is larger in the L-mode

phase after H-L transition than that before the L-H transition.

In I-phase of H-mode discharges, the stored energy increases from I-phase to H-

phase, and the toroidal rotation velocities in I-phase are lower than those in H-phase.

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Thank you for your attention!