D. A. Rasmussen, NCSX Research Forum 2006 Page 1Columbia U.

ECH and Fast Wave Electron Heating Systems for NCSX

Tim Bigelow, Dave Rasmussen, Phil Ryan, Mike Cole ORNL

Joel Hosea, Elmer Fredd PPPL

D. A. Rasmussen, NCSX Research Forum 2006 Page 2Columbia U.

• Utilize existing standalone gyrotron @28 GHz

– 40 kW for 500 ms.

– Socket can be upgraded to 200 kW with HV supply

• Replace 25 kA ohmic First Plasma scenario with currentless ECH

• Eliminates iota profile control complications from ohmic currents

• ECH could be used to selectively heat passing or trapped

populations for confinement studies.

• Low power CW ECH at low B field may be a useful for vessel

conditioning

28 GHz ECH has multiple applications on NCSX

D. A. Rasmussen, NCSX Research Forum 2006 Page 3Columbia U.

Standalone - Gyrotron, HV power supply socket, magnet, water manifold

Footprint is 4’x6’

Controls, magnet, waveguide all compatible with 200 kW cw power upgrade at 28 GHz using existing PPPL supplies

D. A. Rasmussen, NCSX Research Forum 2006 Page 4Columbia U.

MODEABSORBER

TBD

TE02-TE01MODE

CONVERTER

28-GHZGYROTRON200-KW

TE02 MODE

WAVEGUIDEMODE

ANALYZER

?

BLOCK DIAGRAM PROPOSED NSTX 28 GHZ ECH SYSTEM

TE01 TO TM11 TO HE11CURVED WAVEGUIDECONVERTER SECTION

WITH HE11 RADIUS BEND

PLASMA

CORRUGATED WAVEGUIDE

TAPER TAPER

FOCUSING MIRROR

WINDOW

6.35 CM WAVEGUIDE

TAPER

ARC DETECTORSECTION

TE02 Corrugated bend

Inside vacuum

Waveguide and launcher configuration

Block Diagram - Proposed NCSX 28 GHz ECH System

D. A. Rasmussen, NCSX Research Forum 2006 Page 5Columbia U.

ATF ECH launcher

A modified version of the ATF ECH launcher could be used on NCSX

D. A. Rasmussen, NCSX Research Forum 2006 Page 6Columbia U.

ICRF fast wave heating on NCSX with a 57 MHz FWG antenna

• 2-4 MW of tunable ICRF transmitters located adjacent to NCSX test cell (can be retuned in ~ 1 month)

• Utilize direct electron heating mode at 57 MHz, 0.5 -1.2 T

• IBW mode may also be feasible• Tilt antenna to match edge field line pitch• 40 kW 28 GHz startup could provide adequate

target plasma• Loading modeling for startup and other target

plasmas can be done by M. Carter

D. A. Rasmussen, NCSX Research Forum 2006 Page 7Columbia U.

57 MHZ FOLDED WAVEGUIDE

• Monopole or dipole face plates provide options on wave launch spectrum

• Rear coaxial feed and coupling loop• Vacuum tank to enclose antenna allows

arbitrary antenna rotation angle

QuickTime™ and aPhoto - JPEG decompressor

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QuickTime™ and aPhoto - JPEG decompressor

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Monopole

Dipole

-30

-20

-10

0

Bz pattern (dB)

-20 -10 0 10 20

Scan Position (cm)

DIPOLE

MONOPOLE

D. A. Rasmussen, NCSX Research Forum 2006 Page 8Columbia U.

FWG can be mounted on a NB port

12.375

12.375

57 MHz Folded Waveguide

ICRF Launcher shown in

NCSX Port "NB" centerline

FWG rotated to match

field lines at plasma edge

• 57 MHz folded WG will fit on NCSX NB port• Coils and cryostat do not appear to interfere• Folded WG can be rotated in port for field line optimization and IBW experiments

D. A. Rasmussen, NCSX Research Forum 2006 Page 9Columbia U.

Approximately to Scale drawing of FWG on

NCSX NB port

FWGbody

Existing FWGVacuum tank

Coaxial RF feed line

Vacuum InterfaceFlange and in-vesselSupport structure

D. A. Rasmussen, NCSX Research Forum 2006 Page 10Columbia U.

D. A. Rasmussen, NCSX Research Forum 2006 Page 11Columbia U.

PPPL ICRF transmitters can be utilized to drive the FWG

• Two FMIT units• 40-80 MHz • ~ 2 MW each; can be combined• Can be tuned to 57 MHz in < 1 month• Transmission line to NCSX exists to wall• Tuner, RF instrumentation installed and

operational