Download ppt - HHFW Current Drive, RF-Only H-modes, and HHFW+NBI

HHFW Current Drive, RF-Only H-modes, and HHFW+NBI

presented by Phil Ryan (ORNL)for J. Hosea, B. Leblanc, R. Pinsker, D.

Swain, J. R. Wilson, and the NSTX HHFW Team

NSTX Results ReviewSept 20, 2004

HHFW Operation in 2004

• Developed DND HHFW plasma scenarios–Separate plasma fueling from antenna coupling

–Center stack gas injector and DND geometry

• Operated with rtEFIT control of plasma position.

• Installed Langmuir probes at antenna array.

• Extended HHFW CD to higher density, DND plasmas (XP403).

• HHFW Driven H-mode plasma operational envelope expanded (XP425 - Leblanc)

• Combined HHFW-NBI operation (XP413 - Leblanc)

• ERD measurements show ion heating in peripheral region

HHFW CD at kz = 7.6 m-1

HHFW on

1.50

1.25

1.00

0.75

0.50

0.25

0.00

Loop Voltage (V)

0.60.50.40.30.20.10.0

time (s)

cntr-CD

co-CD

8x104

6

4

2

0

Stored Energy (J)

0.60.50.40.30.20.10.0

time (s)

4

3

2

1

0

RF Power (MW)

Stored Energy and RF Power Loop Voltage (corrected for dI/dt)

• Operation at 30% higher density gave ICD ~ 100 kA for P = 4.2 MW (2.7 MW co-CD, 1.5 MW cntr-CD). Te(0) = 1.7 keV, ne(0) = 2.1x1019 m-3, He, double-null diverted, Ip = 0.5 MA, 0.45

T.

Ryan NSTX Results 2004

CURRAY

AORSA

DHe

• CD efficiency lower than predicted by CURRAY ray-tracing code (Mau) and slightly lower than AORSA full-wave code (Jaeger).

• Density-normalized current drive efficiency same as at lower densities in D and He ( = 0.03 x 1019 A•m-2•W-1)

• Double-null and single-null diverted configurations give similar efficiencies.

20022003

2004

HHFW CD efficiency, referenced to total antenna power, is somewhat lower than predicted


Te(0) = 2 keVkz = 7.6 m-1

2.0

1.5

1.0

0.5

0.00.60.50.40.30.20.10.0

time (s)

6

5

4

3

2

1

0

Central Electron Temperature

-30º-90º

ohmic

112326112327112328112336

6

5

4

3

2

1

00.60.50.40.30.20.10.0

time (s)

6x104

5

4

3

2

1

0

Total Stored Energy

-30º-90º

ohmic

112326112327112328112336

Line-average density3.0x1015

2.5

2.0

1.5

1.0

0.5

0.00.60.50.40.30.20.10.0

time (s)

6

5

4

3

2

1

0

ohmic

-30º-90º

112326112327112328112336

HHFW operation at kz = 3 m-1 failed to heat central electrons

• CURRAY and AORSA calculations predict greater current drive efficiency for Te(0) ~ 2 keV.

• Plasma was pre-heated to Te(0) ~ 2 keV with 2.5-3 MW of HHFW for 100 ms at -90º phasing (-7.6 m-1).

• Fast switching to 1.7 MW at -30º (-3 m-1) caused a rapid collapse of Te and an increase in <ne>.


RF

Po

we

r (M

W)

RF

Po

we

r (M

W)

RF

Po

we

r (M

W)

-90º -30º

Density Contours From Reflectometer

Onset of rf steepens edge profiles

Phase shift has little effect on edge profile

Driven H-mode and NBI-Combined Heating Summary

Preliminary Data - Leblanc

• HHFW Driven H-mode plasma operational envelope expanded

– Ip ≈ 0.6-0.8 MA, BT ≈ 0.45 T, medium density DND

– k// = 14 and 7 m-1 at Ip = 0.6 MA

– k// = 14 m-1 at Ip = 0.8 MA

• Combined HHFW-NBI operation

– Developed 2-beam reduced energy scenario compatible with HHFW antenna operation

– NBI into HHFW pre-heated plasmas

• Wmhd and neutron rate increases observed

• Low efficiency

– HHFW into NBI-drive H-mode plasmas

• Wave do no seem to reach plasma core

BPL-NSTX-Res-Sep-2004

HHFW H-mode at 0.7 MAHHFW with beam blips, k// = 14 m-1, 1.5 MW


HHFW Driven H-mode at 0.8 MAHHFW only, k// = 14 m-1, 2.0 MW


NBI Pulses into HHFW Heated PlasmaObserved Wmhd and Neutron (Sn) Increases

Sn increase larger than for Wmhd


HHFW into NBI Driven H-mode PlasmaSmall Effects On Wmhd and Neutron (Sn) Are Reproducible

Seem more compatible with edge effects than heating
