Recent Results and Prospects for Correlation ECE ... Recent Results and Prospects for Correlation...

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  • Recent Results and Prospects for Correlation ECE Measurements on TCVCorrelation ECE Measurements on TCV

    L. Porte1, S. Coda1, T.P. Goodman1, A. Pocehlon1, V.S. Udintsev2, V. Vuille1, , , , ,

    1Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches enEcole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom‐Confédération Suisse, CH‐1015

    Lausanne, Switzerland

    2ITER Organization, Building 519/122, CHD, Diagnostics Division Route de Vinon sur Verdon ‐ 13115 St Paul Lez Durance ‐ France

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 1/17

  • OUTLINE OF THE TALK

    TCV overview

    ● CECE capability on TCV

    ● summary of measurements to date

    ● collisionality● collisionality ● shaping (triangularity) ● poloidal angle w.r.t. line of sight

    radial correlation length● radial correlation length

    ● conclusions from recent measurements

    ● future plans

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 2/17

  • TCV : transport as a function of form

    Ip  1MA (400kA typical)

    ● Bt < 1.45T

    ● R = 0.88 m, a = 0.25 m, R/a ~ 3.5

    ● elongation 0.9 <  < 1.85g

    ● triangularity - 0.7 <  < 1

    ● negative triangularity H-mode

    ● single/double null

    d bl t● doublet

    ● snowflake

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 3/17

  • TCV ECRH/ECCD X2 + X3 4.5MW : Flexible system  f l t l h ti d t d ifor plasma control, heating and current drive

    3 gyrotrons● 3 gyrotrons ● 450kW ● steerable launcher (real-time)

    X d b t bit il h● X-mode but can arbitrarily change ● 2 sec.

    ● 6 gyrotrons● 6 gyrotrons ● 100kW < P < 450kW ● real-time control (F Felici 09:00 Wednesday)(F. Felici 09:00 Wednesday)

    power launcher angle ( l i ti )(polarisation) pulse rate

    ● 2 sec.

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 4/17

  • MEASUREMENTS ON TCV: motivation

     = + 0.4 0.4 ● increasing eff decreases thermal diffusivity (e)

    ● factor 2 decrease in e from positive to negative triangularity

     = - 0.4 ● is there a measurable trend in electron turbulence as function of eff or in δ ?

    ( )

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 5/17

    Y. Camenen et al; Nucl. Fusion 47 (2007) 510–516

  • MEASUREMENTS ON TCV : reduction in  icross power as υeff increases

    n = 1 1 x 1019m-3 ; T = 1 3keV ne= 0.9 x 1019m-3 ; Te = 1.8keV

    -40 (H

    z- 1 )

    ne= 1.1 x 10 m ; Te = 1.3keV -45

    r d en

    si ty

    -50

    ra l p

    ow er

    -55

    ss s

    pe ct

    r

    -60

    lo g.

    c ro

    s

    20 40 60 80 100 120 140 1600 Frequency (kHz)

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 6/17

  • MEASUREMENTS ON TCV : dramtatic d ti i L ireduction in Lc as υeff increases

    A.Pochelon, 52rd APS DPP, 8‐12 Nov. 2010, Chicago, NI2 6

    at given power, Lc very sensitive to density, which needs to be well controlled

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 7/17

  • MEASUREMENTS ON TCV: δ scan P fil t l i ECHProfile control using ECH necessary

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 8/17

  • MEASUREMENTS ON TCV: large reduction in  t b l i f t δturbulence on going from +ve to ‐ve δ

    y ow

    er

    D en

    si t y

    C ro

    ss P

    o S

    pe ct

    ra l

    Fluctuation level too low for good estimate of Lc in this run.

    C S

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 9/17

  • CECE ON TCV : the measurement of turbulence

    • single,fixed, Gaussian-beam line-of-sight measurement from LFS

    • 2 tunable, narrowband (170 MHz) YIG filters

    • range 69-81GHz 0 0

  • RECENT MEASUREMENTS ON TCV: poloidal angle

    LORB GK i l li l b l [C n = 2

    ● LORB GK simul. linear, global [Camenen, Bottino05] show spatial structure of instabilities at varying poloidal wave number

    n   2

    ● at differing poloidal angle (plasma height) might expect to be able to measureexpect to be able to measure

    either spectral differences in turbulencen 10 spectral differences in turbulence

    or radial extension of modes (correlation l th)

    n = 10

    length)

    ● conduct an extensive set of measurements to examine the experimental feasibility of this idea

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating

    A.Pochelon, ITC‐21, Toki, Japan, Nov. 28 2011

    11/17

  • RECENT MEASUREMENTS ON TCV: poloidal angle

    # 43131 Z = 17cm

    # 43497 Z = 0cmTe(keV)

    vol

    ne(x1019)

    ()  0 7 ( ) 0 7()  0.7  3 fece 75.5GHz

    ()  0.7  3 fece  71.5GHz

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating

    vol 12/17

  • RECENT MEASUREMENTS ON TCV: poloidal angle S i i t l t tSurprising spectral content

    -50

    -55

    ct ru m   ● some increase in amplitude

    away from Z=0

    -60

    w er  S pe

    c # 43123 ● distinct changes in the spectral content

    -65

    Cr os s  Po

    w

    ● at Z= 0 lower high n content than off-axis

    -75

    Lo g  C

    # 43497 ● unexpected observation

    20 60 100 140 180

    -75

    Frequency (kHz)

    # 43497

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 13/17

    Frequency (kHz)

  • RECENT MEASUREMENTS ON TCV: poloidal angle L i l id l l h

    Z 0 ; L  (1  0 06) cm

    Lc varies as poloidal angle changes

    Z = 0 ;  Lc  (1  0.06) cm Z = 5 ;  Lc  (1.9  0.6) cm Z = 10 ; Lc  (1.6  0.3) cm

    ( )Z = 17 ; Lc  (1.7  0.9) cm

    ci en

    t

    ● attempt made to estimate di l l i l h f

    on  c oe

    ff i

    (15 – 120) kHz

    radial correlation length of turbulence

    co rr el at io ● can resolve differences

    between plasma height

    Lo g.  o f c

    (15 – 60) kHz ● need more data points in the scan but very time consuming with only two channels

    Radial separation of resonances (cm)

    with only two channels

    Radial separation of resonances (cm)

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 14/17

  • CONCLUSIONS FROM RECENT MEASUREMENTS d t i diff t l igood measurements in different plasma scenarios 

    CECE on TCV● CECE on TCV

    (i) measured factor 2 reduction in Lc by increasing eff

    (ii) measured reduction in turbulent amplitude at mid-radius between +ve and –ve δ+ve and ve δ

    both of these observations are consistent with global measurements of electron energy confinement

    (iii) observed changes in spectral content of turbulence in moving from(iii) observed changes in spectral content of turbulence in moving from z=0 to z=17 w.r.t. plasma mid-plane : needs more work to explore and confirm these observations

    (iv) measurement of Lc at different poloidal angle (plasma height)

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 15/17

  • FUTURE PLANS: 4 new channels & 2 new mixers will install 4 additional channels to have 6 channels in all1

    two new mixers and front end amplifiers for the front end of the CECE● two new mixers and front end amplifiers for the front end of the CECE diagnostic1

    at present signal shared between CECE and standard ECE radiometer so signal loss is an issueat present signal shared between CECE and standard ECE radiometer so signal loss is an issue

    will allow measurements over a broader range of the plasma volume (HFS & LFS measurement)

    1 EFDA support granted for these equipment purchases

    Radial coverage for Lc measurement i h tin one shot

    07/06/2012 17th Joint Workshop on Electron Cyclotron Emission and 

    Electron Cyclotron Resonance Heating 16/17

  • FUTURE PLANS: high gain a