LCDC IN TOKAMAKS. THE LOCAL COLD AND DENSE COMPRESS What to Measure and How to Measure. Waseda University 2

Transcription

1 EPS Fuelling Workshop LCDC IN TOKAMAKS THE LOCAL COLD AND DENSE COMPRESS What to Measure and How to Measure M.Irie 1 & M.Kubo-Irie 2 1 Waseda University 2 Denji Ohyoh Kenkyuujyo (Research Institute for Applied Electro-Magnetism) CRETE GREECE

2 LCDC THE LOCAL COLD AND DENSE COMPRESS

3 The injected pellet goes under intense heat up and is ablated by bulk plasma and evaporated. The emitted molecules form dense plasmoid surrounding the pellet core. The molecular and the electron density is in the order of /m 3. The molecular density is still very low compared with the pellet core ( /m 3 ), but it is 10 4 times higher than the main plasma ( /m 3 ).

4 CARBON The spectral intensity suggests electron density distribution can be estimated to be Gaussian in the first approximation. Studies of Three Dimensional Cloud Structure of Carbon Pellets Ablated in the W7-AS Plasma, V. M. Timokhin, et al, State Polytechnical University of St. Petersburg, Russia

5 Plasmoid deformation from the spheroid shape is large but how about the LCDC? ASDEX hydrogen pellet Investigation of Cryogenic Pellet Cloud Dynamics(EPS2004) S. Kálvin, el al., KFKI-Research Institute for Particle and Nuclear Physics, EURATOM Association, Budapest, Hungary

6 Pellet Injection in ALCATOR Li pellet This figure suggests that the LCDC plasma has high aspect ratio in the magnetic field direction. Poloidal Drift of Striations in Li+ Pellet Ablation Clouds Brock Bose, et al., PSFC(APS2003) 003/BosePoster.pdf

7 Neutral deuterium radiation measurement requires sub-ns time resolution if we require time development. Time History of Deuterium Pellet Ablation TEXT R. D. Durst et al. Nuclear Fusion 30, P.3 (1990) How about the ions released from the plasmoid zone?

8 Cold and dense electron components are trapped by the magnetic field within the Larmor radius around 1 μm and freely diffuse with 10 3 m/ms in the magnetic field direction and forms homogeneous Cold and Dense Compress except the local rational surfaces, where narrow high density filamentary plasma channel are formed. Electron density is about 4 orders of magnitude higher than the bulk plasma.

9 q=2.00 q=2.10 q=2.20 LCDC electrons diffuse along the field line and virtually covers the magnetic surface except the rational surface as shown here.

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11 Closed flux tubes keep the charged particles from diffusion LCDC And Density Slit

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13 Diagnostics LCDC is predictable in the first approximation.

14 How stable is the main plasma configuration? Is the electron thermalization ( LCDC heating up) efficient? Electrons density in the bulk plasma is extremely low to heat up times dense electrons.

15 1. Many observed pictures of pellet ablation from visible spectra is available in the internet. 2.We would like to know about the thermalization and diffusion process of the cold and dense plasma. 3. Experimental results on the continuum radiation is very limited /m 3, 10 0 ev plasmoid should be easily detectable!?

16 How about Continuum radiation? Continium radiation measurement in ASDEX-U W.M.Muller et al. Phys.Rev.Lett, 83,p2199 (1999)

17 FRAME RATE (fps) Time resolution ( Vertical Pixels) Even the consumer level CMOS camera can trace sub-ms LCDC phenomena. (EPIX SV642C Horizontal: 124 pixel)

18 Spatial resolution: 3D reconstruction Step.1 Geometrical optics Step.2 Wave optics. Step.3 Quantum Optics : Photon Phase Passive Holography Fundamental Example is the well known Double Slit Experiment.

19 In human eye, we can imagine the line of sight distance from the picture taken by large aparture / small f-number. Tandem-camera system with computer system can be used in place of human imagination.

20 LCDC zone can be predicted and can be found at least near the pellet path. Density distribution and time history is predictable in the first approximation.

21 BLUR: Convolution Integral Image point contains off-focus information Step.1 : Within geometrical optics

22 OFF-FOCUS CAMERA SETTING with image rotation

23 Build-up of an electron interference pattern. Numbers of electrons (Electron Beam version of Young s Double Slit ) are 10 (a), 200 (b), 6,000 (c), 40,000 (d), and 140,000 (e). A. Tonomura, "Direct observation of hitherto unobservable quantum phenomena by using electrons," Proc. Natl. Acad. Sci. USA 102 No. 42 (2005):

24 CONCLUSION We have introduced the fundamental diagnostic plans for THE LOCAL COLD AND DENSE COMPRESS