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ELECTRON CYCLOTRON SYSTEM FOR

KSTAR

US-Korea WorkshopOpportunities for Expanded

Fusion Science and Technology Collaborations

with the KSTAR ProjectPresented by

Richard Callis

General AtomicsMay 19, 2004

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ELECTRON CYCLOTRON HEATING IS AN IMPORTANT TOOL FOR ADVANCED

TOKAMAK RESEARCH

• Effective source of highly localized and controlled heating and current drive– Plasma heating

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• Effective source of highly localized and controlled heating and current drive– Plasma heating– Current profile control and

sustainment

ELECTRON CYCLOTRON HEATING IS AN IMPORTANT TOOL FOR ADVANCED

TOKAMAK RESEARCH

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• Effective source of highly localized and controlled heating and current drive– Plasma heating– Current profile control and

sustainment– Control of MHD instabilities

ELECTRON CYCLOTRON HEATING IS AN IMPORTANT TOOL FOR ADVANCED

TOKAMAK RESEARCH

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• Effective source of highly localized and controlled heating and current drive– Plasma heating– Current profile control and

sustainment– Control of MHD instabilities

• Coupling of power to the wave is easy– Wave propagates in vacuum,

remote antennas, insensitivity to plasma edge

ELECTRON CYCLOTRON HEATING IS AN IMPORTANT TOOL FOR TOKAMAK

RESEARCH

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• Effective source of highly localized and controlled heating and current drive– Plasma heating– Current profile control and

sustainment– Control of MHD instabilities

• Coupling of power to the wave is easy– Wave propagates in vacuum,

remote antennas, insensitivity to plasma edge

• Power density can be very high (~109 W/m2)

ELECTRON CYCLOTRON HEATING IS AN IMPORTANT TOOL FOR ADVANCED

TOKAMAK RESEARCH

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THE ABILITY TO MODIFY THE CURRENT DENSITY PROFILE IN A HIGH PLASMA HAS BEEN

DEMONSTRATED

• Increased negative central shear leads to increased core confinement

• fNI > 85% with nearly stationary profiles

• Off-axis co-ECCD increases negative central shear

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NEGATIVE CENTRAL SHEAR SUPPORTS FORMATION OF INTERNAL TRANSPORT

BARRIERS

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PINPOINT LOCALIZATION OF EC POWERSUPPORTS STABILIZATION OF MHD MODES

• Stabilization of neoclassical tearing modes uses ECCD inside magnetic islands– Leads to higher operation– Avoids plasma disruptions (2/1

modes)

• Accurate placement of ECCD is required to hit island– Real time feedback schemes

developed

• Interaction of wave with instability allows measurement of mode onset conditions and growth rates for comparison to theory

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ACTIVE TRACKING OF RATIONAL SURFACE MAINTAINS BENEFITS OF STABILIZING THE 3/2 NTM

• m=3/n=2 NTM suppressed by ECCD using feedback to optimize the location

• After mode disappears active tracking keeps ECCD on q = 3/2 surface

• N can be raised above the onset condition even in the presence of sawteeth and ELMs

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THE PROPOSAL IS FOR THE US TO PROVIDE KSTAR WITH A TURN-KEY 4 MW

170 GHz EC SYSTEM BY 2010

• Four 1 MW 170 GHz gyrotrons identical to those developed for ITER

• Each gyrotron will use an IGBT solid state modulator, also an ITER design

• The transmission line will use evacuated waveguide components identical to that used on ITER

• The Antenna will be custom designed for KSTAR but adapted from the remote steering concept being used by ITER for the upper ports. An alternate design based upon the ITER midplane antenna will be evaluated prior to the start of detailed design.

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THE GYROTRON SYSTEM WILL BE BASED UPON THE DEMONSTRATED HARDWARE

BUILT FOR DIII-D AND ITER

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THE GYROTRON POWER SUPPLY IS ALL SOLID STATE BASED UPON THE PROPOSED ITER

POWER SUPPLY CONFIGURATION

3 PHASERECTIFIER

STEPUP XFMR

CIRCUITBREAKER

DISTRIBUTIONXFMR

FAST SERIES SWITCHSWITCHING BUCK REGULATOR

DC - DC PULSE WIDTH MODULATOR POWER SUPPLY-40 to -85 KVDC 40 A

-100 KVDC160 A

20 kV50 mARegulatedPower Supply

20 kV50 mARegulatedPower Supply

20 kV50 mARegulatedPower Supply

20 kV50 mARegulatedPower Supply

Gyrotron Power Supply No 1

Gyrotron Power Supply No 3

Gyrotron Power Supply No 2

Gyrotron

•Single large transformer rectify feeding individual power supplies

•Power supplies are IGBT based Pulse Width Modulation design

•Gyrotron is protected from spark-down by a fast IGBT opening switch

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THE EC TRANSMISSION LINE WILL BE ASSEMBLED FROM THE SAME

COMPONENTS APPLICABLE TO ITER

Waveguide Switch

Step corrugated vacuum waveguide for various

wavelengths

A power monitormiter bend is thefirst miter in each waveguide line.

Standard miter bend. Grooved rotating mirrorscreate polarization control miters.

Waveguide switchwith 70 dB isolation

waveguide bellowsare used wheretransmission linemovement is identified

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THE LONG PULSE LAUNCHER WILL BE BASED UPON THE ITER REMOTE

STEERABLE LAUNCHER CONCEPT• The launcher uses a

square corrugated waveguide of a length such that the exit beam mimics the input beam.

• Steering mirrors are located outside the vacuum vessel far from plasma disruption and heat loads.

• Scanning is limited to ±10° in all directions

• A fixed mirror at the plasma end of the square waveguide points the beam in the nominal direction

Circular waveguide

CVD window

Fixed mirror

Square waveguide

± 10°

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A TURNKEY 4 MW 170 GHz ECH SYSTEM FOR KSTAR WOULD COST $19 M

•Prices are in $2004•Cost savings are assumed, because hardware is identical to ITER EC hardware and could be built at the same time, so quantity discount maybe applicable.

•Design and documentation is for KSTAR specific issues only, ITER covers major R&D costs.

•Installation supervision only, KSTAR is to cover cost of installation labor

GYROTRON SYSTEMS

POWER SUPPLIES

TRANSMISSION LINES ANTENNA TOTAL

PHYSICS SIM 200

DESIGN & DOC 528 600 237 678 2043

FABRICATION 7456 2611 3528 2245 15841

INSTALLATION* 366 682 125 200 1373

TOTAL 8,350$ 3,893$ 3,890$ 3,123$ 19,456$

KSTAR COST SUMMARY (k$)

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FOR THE GYROTRON SYSTEM THE MAIN COST IS WITH THE GYROTRONS AND

SUPERCONDUCTING MAGNET

GYRORON & MAGNET 5028SUPPORT TANK 358INST/CONTROL 1843

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THE 4 MW ELECTRON CYCLOTRON SYSTEM FOR KSTAR COULD BE READY

FOR EXPERIMENTS BY 2010

KSTAR 4 MW EC SCHEDULE 2005 2006 2007 2008 2009 2010

PHYSICS SIMULATION

RF SOURCES & CONTROLSDESIGN/TEST

PRODUCTION/FABINSTALLATION/CHECKOUT

POWER SUPPLIESDESIGN/TEST

PRODUCTION/FABINSTALLATION/CHECKOUT

TRANSMISSION LINES DESIGN/TEST

PRODUCTION/FABINSTALLATION/CHECKOUT

ANTENNA DESIGN/TEST

PRODUCTION/FABINSTALLATION/CHECKOUT

COST (k$2004) 200 1800 6000 6000 5000 500

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SUMMARY

• Steady State Advanced Tokamak plasma research on KSTAR could be advanced by five or more years if the US contributed to a 4 MW EC system based upon the ITER design.

• The EC technology intended for ITER will receive real hands on testing, years before needed for ITER, allowing for improvements to reliability and performance.

• The cost (in 2004 $) would be ≈$19M, but could be lowered if Korea could support some of the costs, such as gyrotrons and power supplies.