Collective Thomson Scattering Study using f0+df f0+df+fs gyrotron df~200MHz power monitor ECRH Transmission

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  • Shin KUBO, Masaki NISHIURA, Kenji TANAKA, Takashi SHIMOZUMA, Yasuo YOSHIMURA, Hiroe IGAMI,

    Hiromi TAKAHASHI, Takashi MUTOHNational Institute for Fusion Science

    Collective Thomson Scattering Study using Gyrotron in LHD

    Research Center for Development of FIR Region, Univ. of FukuiYoshinori TATEMATSU, Teruo SAITO

    Namiko TAMURA,Dept. Energy Science & Technology, Nagoya Univ.

    US-Japan Workshop on RF Physics2010.03.8-10 General Atomics, San Diego

  • Contents

    ECRH System in LHD --> Potential as a diagnostic toolCollective Thomson ScatteringReceiverPreliminary resultsScattering Volume and CTS spectrumSub-Tera Hz Gyrotron DevelopmentFuture PlanSummary

  • ECRH System

  • Design of the Antenna System of ECRH in LHD

    Two sets of upper antennas from 5.5U and 9.5 U port for 82.7GHz and 168GHz

    Two 84 GHz Antenna from 1.5 L port

    All antennas can focus and deposit the power within r

  • 6

    Elliptical Gaussian Beam Focusing Scheme

    168GHz Beam

    SteeringMirror

    FocusingMirror

    from Waveguides

    84GHz Beam

    SteeringMirror

    FocusingMirror

    mid-plane Focusing MirrorBi-foc

    al Mirror

    Waveg

    uide m

    outh

  • Hot test of beam steering/focusing Errors of steering for tor/rad-directions notably affect deposition profile Beam steering/focusing were checked in vacuum vessel of LHD by using

    Kapton film and IR-camera.

  • ECRH Beam as a Scattering Probe Beam Well defined beam for heating is also suitable

    for probe beam for scattering measurement. High power density, High Frequency

    Modulation Good S/N Ratio

    Controllable Scattering Cross Section Position Scattering Angle

    Promising Candidate for Density Fluctuation Measurement

    Structure study of micro-turbulence Wave detection

    EC wave, LH wave, IC wave, Alfven wave Collective Thomson Scattering

    Ion temperature measurement Alpha particle distribution study

    EC wave, LH wave, IC wave, Alfven wave

  • 9

    Collective Scattering using

    ECRH System

  • 10

    Collective Scattering Condition

    3

    =10 deg =90 deg

  • 11

    LHD ECH Antenna Configuration (2008)

    9.5U Antennaout 82.7 GHzin 77 GHz

    5.5U Antennaout 82.7 GHzin 168 GHz

    1.5L Antennaout 84 GHzin 84 GHz

    2-O Antennaright 77 GHzleft 168 GHz

    3.5 inch corrugated WG

    3.5 inch corrugated WG

    3.5 inchcorrugated WG

    1.25 inch corrugatedWG

  • 12

    LHD ECH Antenna used for probe and receiving beams

    3

    9.5U Antennaout 82.7 GHzin 77 GHz

    5.5U Antennaout 82.7 GHzin 168 GHz

    1.5L Antennaout 84 GHzin 84 GHz

    2-O Antennaright 77 GHzleft 168 GHz

    3.5 inch corrugated WG

    3.5 inch corrugated WG

    3.5 inchcorrugated WG

    1.25 inch corrugatedWG

    waist size 0.015 mwaist size 0.02 m 0.8 MW/5s, 0.24 MW/CW

  • 13

    Present ECRH System in LHD

    Two sets of transmission line/ antenna are installed on the ports. 9.5U, 5.5U 1.5L and 2O

  • 14

    Proposed Scattering Probe/Receiving transmission Line

    A set of transmission line/ antenna on the 9.5U port is used for CTS.A line which 77GHz 1MW power available is used for probe beam

  • 15

    Receiver Setting Configuration

  • 16

    Attached Receiver System

  • plasma

    f0+df

    f0+df+fs

    gyrotrondf~200MHz

    power monitor

    ECRH Transmission line(corrugated waveguide)

    fixed local oscillatorstability < 10 MHz

    pin SW

    Notchfilter

    Att. BPF

    WG SW

    Filtek HPF

    fl=78 GHz

    Mixer

    A1

    A2A3

    Isolator

    Two way divider 1

    Two way divider 2

    high freq.

    low freq.

    500-200

    900-200

    1300-200

    1700-200

    1900-100

    2100-100

    2300-100

    2500-100

    Four way divider Diodes

    Video Amps.(x1000)

    monitor port

    measure port

    A1: Cernex CBLU1103030-01A2: Cernex CBLU1103050-01A3: Amplitek apt4_SN104331

    Heterodyne Receiver for Collective Thomson Scattering in LHD (2008)

  • Filter CombinationLocal Oscillator 74 GHz

    Filter combinationCenter freq.

    IF 3 GHzsensitive low freq. IF

    for high energy ionsnarrow band dense near center freq. IF

    for bulk ionwide band sparse at peripheral IF

    for high energy ions

  • Actual Receiver Configuration

    IF Amps.

    WaveguideSwitch

    Splitters

    Filters

    Mixer

    Local Oscillator

    PIN Switch

    Notch Filter

    Horn Antenna

    Waveguidefor Probe

    Beam

    From 77 GHz Gyrotron

  • During the first trial of CTS measurement,the local oscillator of 74 GHzwas damaged,

    Actual Filter Combination

    and switched tentatively to78 GHz Courtesy of Dr. T. Tokuzawa

  • Ch.1,4,5 double side bandCh.2,3,6-8 lower side band

    Background, calib.

    CTS componentAll channel lower side band Ch2,3 almost notched

    10-3

    10-2

    10-1

    100

    0 1 2 3 4 5 6 7 8 9

    %) /# &)*312!( $,( "'.0-/, '.+, &)*312 !( $,( "

    Cal.

    Fact

    or(V

    /eV)

    Channel

    2009.01.23T=210 deg. lock-in factor=3.0

    Effect of Notch Filter

    Actual Filter Combination and Calibration with Liq N2

  • 78GHz local combination

    Measured Notch FilterCharacteristics Courtesy of Prof. A. Mase

    FilterCharacteristics Courtesy of Prof. Y. NagayamaDr. T. YoshinagaMr. D. Kuwabara

  • Actual Measurement Configuration

    B=2.75 TR=3.6 mrho=0.70.2k ~ perpendicular

  • 25

    Preliminary Results

  • B=2.75T, R=3.6mFundamental ECRH Plasma

    Fundamental ECRH plasma B=2.75T, R=3.6mFundamental ECRH Plasma Noise well suppressedSpikes at every modulation turn-on, off

    due to spurious mode oscillation from gyrotronremovable by pin switch

    Fundamental ECRH plasma (double side band factor)

  • Expanded in time (#91758)

  • Expanded in time (#91758)

  • CTS #91758 (double side band factor)

    B=2.75T, R=3.6mFundamental ECRH Plasma Noise well suppressedSpikes at every modulation turn-on, off

    due to spurious mode oscillation from gyrotronremovable by pin switch

  • CTS #91758 (double side band factor)

    B=2.75T, R=3.6mFundamental ECRH Plasma Noise well suppressedSpikes at every modulation turn-on, off

    due to spurious mode oscillation from gyrotronremovable by pin switch

  • Analysis ECRH plasma

    Decompositionof scattering

    component from heating/heat

    wave componentis necessary

  • Method of analysis Raw data of several modulation periods are

    rearranged in time relative to the turn on/off time

    These rearranged data are fitted with the function

    a corresponds to background increments/decrements due to heating (change in slope)

    b corresponds to increment/decrement due to scattered signal over background (stepwise change)

  • Example of deduced raw signal change

  • Spectrum change in time

  • Example of deduced scattered power spectrum

  • 36

    Receiver Improvements

  • Heterodyne Receiver for Collective Thomson Scattering in LHD (2009)

    fixed local oscillatorstability < 10 MHz

    pin SW

    Notchfilter

    Att.

    BPF

    WG SW

    fl=74 GHz

    MixerIsolator

    HPF

    A1 A2

    A3

    A4A4

    A4A4

    A4A4

    A4A4

    A3

    n

    ECRH Transmission line(corrugated waveguide)

    5th-HarmonicMixer

    n

    fl1-ndf

    A5

    HPF

    Att A5

    HPF *

    HarmonicMixer

    Error AmpVoltage Controlled

    Oscillator

    plasma

    f0+df

    f0+df+fs

    gyrotrondf~200MHz

    power monitor

    ADC

    ADC

    ADC

    ADC

    32 channel VideoAmp.(x100)

    LPF

    Filters

    Low NFAmps

    PowerAmps

    2

  • Increased IF bands local frequency = 74.00 GHz

  • IF filter characteristics

  • 40

    Scattering Volume Key to confirm scattering signal

    confirmation Necessary for absolute calibration

  • Beam Cross Section Controlled by beam steering

    receiving beamprobing beamprobing beam receiving beam

    =1.0

    =0.19.5U in 77GHz injection9.5U out receiving

    Max cross section at =0.75 Zero cross section

  • Scattering power is obtained using scattering form factor

    : geometrical factorre: classical electron radiusne: electron densityd: band widthrR: beam radiuss0: wavelength of scattered

    radiationS(k,): scattering form factor

    Probebeam

    Scatteredbeam

    fromGyrotron

    toReceiver

    SN ratio of CTS

  • 43

    Scattered Power

  • U-antenna for 168 GHz used for 77 GHz Scattering

    Beam evolution is recalculated with the 168 GHz antenna mirror configuration radiated from the same waveguide mouth for 77 GHz beam Resultant beam sizes on the mid-plane are 20 mm in radial 99 mm in toroidal

    If the configuration of the mirrors and optical axis are the same,i. e. cos and are kept ,relation between Rin and Rout are defined by

    even for different frequency, or beam size

    77 GHz168 GHz

    bi-focal mirrorfinal focus mirror

    7777

  • 45

    Scattering using Gaussian Beam

  • 46

    Cross Volume of Gaussian Beam

  • 47

    Surface of Cross Volume

  • 48

    Cross Volume and resolution

  • 49

    Scattering using Gaussian Beam

    Scattering Length

  • 50

    Scattered intensity and effecti