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Status of a programme for development of ITER relevant diagnostics onFTU

Status of a programme for development of ITER relevant diagnostics onFTU. Francesco Paolo Orsitto ENEA Frascati(Italy). motivations.

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Status of a programme for development of ITER relevant diagnostics onFTU

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  1. Status of a programme for development of ITER relevant diagnostics onFTU Francesco Paolo Orsitto ENEA Frascati(Italy) 12 ITPA princeton 26-30march07

  2. motivations • Because of the relatively harsh environment of ITER, the implementation of diagnostics on the machine is a major challenge, arguably the most difficult ever undertaken in plasma diagnostics. New diagnostic techniques, components, sensors etc, which are better suited to the environment, are needed. These have to be developed and validated on today’s tokamaks. • FTU is a medium sized device (BT≤8T,Ip=1.6MA,R0=0.93m/a=0.33m,Paux=4.6MW) • some of the FTU parameters similar to ITER : density( nemax > 1 10 20 m-3), power load( P ~10MW/m2) , plasma temperature (Te > 10keV, in scenarios with central ECRH heating), magnetic field 4<BT<8T. • FTU is well placed to contribute to the development of some new ITER relevant diagnostic techniques and components. 12 ITPA princeton 26-30march07

  3. Present status of activity • 1st meeting ( 28 nov 2005) : general discussion of proposals • 2nd meeting (31 march2006) : presentation and discussion of technical details of the proposals already discussed in the 1st meeting. • 3rd meeting (28 june 2006):presentation of the proposal to the ENEA management • Presentation to ITPA TG Dia for advice and collaboration( sept 06) • Discussion inside programme committee FTU (Jan07) • Discussion on management of the programme(Feb07) 12 ITPA princeton 26-30march07

  4. Diagnostics discussed • First mirror test ( G Maddaluno) • Thermography( G Maddaluno) • Techniques of detection of dust by scattering(C Castaldo/E Giovannozzi) • CVD diamond detectors for UV(M Pillon/M Angelone) • Fast wave reflectometry (R Cesario / A Cardinali) • Proposal for evolution of Collective Thomson scattering of FTU in ITER relevant direction ( U Tartari) • Refrattometry to measure the line integral of density( O Tudisco) • Detector GEM to measure X-ray on ITER( D Pacella/ G Pizzicaroli) • Real Time diagnostic system for detection of precursors and reaction to disruptions and fast events of plasma( C Neri, B Esposito, M Riva) • Test of a polarimetric system for ITER( S Segre) 12 ITPA princeton 26-30march07

  5. Priorities • First mirror test ( G Maddaluno) • Fast wave reflectometry (R Cesario / A Cardinali) • Refrattometry to measure the line integral of density( O Tudisco) • Detector GEM to measure X-ray on ITER( D Pacella/ G Pizzicaroli) • Proposal for evolution of Collective Thomson scattering of FTU in ITER relevant direction ( U Tartari) 12 ITPA princeton 26-30march07

  6. First Mirror Test (I)G Maddaluno, M Di Fino,M Montecchi, E Nichelatti,E Serra • Specific features: FTU is a metallic device Mo wall • Wall load >10MW/m2. • The absence of carbon makes interesting the comparison of exposure of mirrors with results obtained in non-metallic devices and very useful for ITER scenarios. 12 ITPA princeton 26-30march07

  7. First mirror test(II) • Experimental system: • It is proposed to use the system for sample introduction which is operating on FTU port#8bottom. • The max diameter of a sample to be exposed is f=25mm • On axis with respect to this system and on the upper port#8 and optical window is available which could be used for a possible real time monitoring of erosion /deposition. 12 ITPA princeton 26-30march07

  8. First mirror test (III) • A facility for construction of mirrors is available at ENEA-Frascati , • Optical tests could be carried out at ENEA Casaccia Labs( North Roma) where equipments are available for measurements of optical figures like reflectance vs wavelength, planarity, roughness. 12 ITPA princeton 26-30march07

  9. Manufacture, characterization and exposure in TEXTOR of Rh-coated molybdenum mirrors Abstract presented at the 34° EPS conference: Tests of rhodium -coated molybdenum first mirrors for ITER diagnostics G. Maddaluno, M. Di Fino , F. Orsitto , A.Rufoloni , M. Montecchi , E. Nichelatti , E. Serra , A. Litnovsky , G. Sergienko , G. De Temmerman , L. Marot In the frame of EFDA taskTW5-TPDS-DIADEV ENEA mirror TEXTOR mirror holder 12 ITPA princeton 26-30march07

  10. Comparison between pre- and after-exposure (to 19 high power NBI-heated discharges) hemispherical reflectance of ENEA Rh-coated Mo mirror 12 ITPA princeton 26-30march07

  11. Techniques for detection of dust by scatteringC Castaldo,E Giovannozzi(ENEA Frascati);S Ratynskaia(MPE Garching); U de Angelis ( Univ of Naples); C Marmolino ( Univ of Molise) • Aim : measurement of size and concentration • Theory of Scattering Lorentz-Mie is used • A Thomson scattering system is proposed 12 ITPA princeton 26-30march07

  12. Proposed Laser light elastic scattering scheme Scattered photons by spherical particle (radius a, refractive index m) Nph≈ Q pa2 (DW/4p) (e/sb) (l/hc) DW ≈ (Dh/h)2/2 ≈ 5 msr Nph≈ 1010 Q a(mm)2 Q = Q(q, a, m) Collection optics (to APD & ADC) h ≈ 50 cm  ≈ p/4 Dh ≈ 5 cm Parabolic & plane Rh-Cu mirrors Laser Beam sb≈ 1 mm2 • 60 Hz Nd:YAG laser beam (TS FTU) • = 1.5 J, t = 20 ns, l = 1.064 mm 12 ITPA princeton 26-30march07

  13. Preliminary results Example of signals due to dusts present in FTU after a disruption. A signal is clearly present in the channel looking at the laser wavelength, and on the other spectral channels, after the end of the plasma current. The signal at the laser wavelength for the central channels. All signal are in counts. 12 ITPA princeton 26-30march07

  14. Percentage of discharges with dust 1322 discharges with a disruption occurring after more than 300 ms from the start of the plasma has been selected. Percentage of discharges with dust seen by the Thomson scattering following a disruption. Only the first 0.5 seconds after disruption has been taken into account. Only 7% of the discharges is without dust (as measured by the Thomson scattering). The average dust density is about 107 m-3. 12 ITPA princeton 26-30march07

  15. Temporal behaviour Normalized number of dust particle in the first 500 ms after disruption compared to the amount of dust in the following 500 ms. The number of dust particles is decreasing in time. 12 ITPA princeton 26-30march07

  16. Spectrometer 12 (central) Discharges with a dust content less than 0.1 (in order to minimize the chances of a double hit) ha been selected. The data are well approximated by a power law with a slope of a= 1.8. The value of s2 ~ 10-4 is inside the Rayleigh approximation (The average value of the laser power has been used). Distribution of Particle radii assuming the Rayleigh approximation. 12 ITPA princeton 26-30march07

  17. Proposal for evolution of Collective Thomson scattering of FTU in ITER relevant directionU Tartari, G Grosso, G Granucci -IFP CNR Milano • A gyrotron based CTS system is installed on FTU and operating . • Working at fgyr<fECE : this configuration is proposed for ITER ( F Orsitto,G Giruzzi Nucl Fus 1997, Bindslev,Meo,Korsholm Feas.Study CTS for ITER 2003, Meo et al RSI 2004, EPS2005 Tarragona, and ITPA meet Culham2005) • Gyrotron used : 140GHz Gycom • The ITER relevant configuration (i.e. fgyr<fECE) can be realized only on a device with high magnetic field like FTU. • Geometry : 90° scattering angle • Aim: measurement of Ti 12 ITPA princeton 26-30march07

  18. proposal • Proof of principle of CTS in X-mode • At high density • Using the ITER configuration • On thermal plasma to measure Ti • On plasmas with non-thermal ions ( when a H beam will be installed on FTU) • With new ( receiving and transmitting) antennas designed to prevent breakdown inside the port. • 1° phase :In the present configuration and with 140GHz gyrotron and • 2° phase: using a 60GHz gyrotron ( and at B=5T) as a true prototype of a ITER CTS system 12 ITPA princeton 26-30march07

  19. Refrattometry to measure the line integral of densityA. Petrov(1), V. Petrov(1), A. Malishev(1), M. De Benedetti, O. Tudisco(2)(1) Triniti, Moscow, Russia.(2) ENEA Frascati • Refractometry is a technique similar to reflectometry, but without any cut-off present into the plasma. • The launched wave is reflected directly by the inner wall of the vacuum vessel. The phase velocity of the wave depends on the refracted index of the plasma, and hence on its density. The Time Of Flight (TOF) refractometer measures the time delay that a small package wave takes crossing the vacuum vassel, that is a direct measure of the wave group velocity. As usual using the cold plasma refractive index the line integrated density can be inferred. 12 ITPA princeton 26-30march07

  20. Proposal • The prototype was tested on FTU using a single frequency( 60GHz, X-mode) but two subsequent phases are envisaged to extract the feature related to the density profile • The proposal is : • 1° phase : to use a two frequency system • 2° phase using a swept oscillator to cover a range of frequencies • 3° phase : a system mounted on a vertical port. 12 ITPA princeton 26-30march07

  21. Prototype and first results on FTU 12 ITPA princeton 26-30march07

  22. Conclusions • A programme of development of ITER relevent diagnostics is proposed by FTU Team. • ITPA TG Diagnostics( and the SWGs) are invited to participate and/or to give advice to define a final version of the programme. 12 ITPA princeton 26-30march07

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