K. Ida

M. Yoshimura

Y. Yoshimura

Ida,  K.

Yoshimura,  M.

Yoshimura,  Y.

NIFS-Repository (National Institute for Fusion Science)

Kinetic modeImaging modeCHSCCD detectorSlit345 678Energy (keV)2-L--without high energy electron--with high energy electronR=0.94mIo10CCD __---..Camera100ReferenceFig. 2 Energy spectrum measured with SX-CCD camera forthe plasma with and without high energy electrons.Fig. 1 Experimental setup of photon counting SX-CCDcamera for the measurements of energy spectrum ofelectrons in CHS.[1] K.Ida and Y.Liang, J. Plasma Fusion Res 79 (2003)345.Ida, K., Yoshimura, M., Yoshimura, Y.§ 16. Measurement of Energy Spectrum ofElectrons Using Photon Counting SoftX-ray CCO CameraExistence of high energy electrons with the large velocityperpendicular to the magnetic field can be important for thetransition from ion root to electron root in the low densityplasma with electron cyclotron heating (ECH). The photoncounting soft X-ray CCD camera has been installed in CHSto study the high energy electrons excited by ECH as shownin Fig.I. Although the photon counting CCD detector hasgood energy and spatial resolution[l], the frame rate of theCCD camera is poor (in a order of 10 second). In order toobtain the spatial and time resolution, a slit parallel to thedirection of major radius, R, is installed between the pinholeand CCD detector and kinetic mode is used as a operationmode ofCCD detector. Then the time resolution is obtainedin the vertical direction of the CCD detector, while thespatial resolution is obtained in the horizontal direction. Thisis the contrast to the normal imaging mode where thevertical direction corresponds to the toroidal direction $.Figure 2 shows a example of the measurements of highenergy electrons near the magnetic axis of the plasma wherethe ECH resonance exist. When the· electron density is highenough (1 x1019m-3), the energy distribution of electronsnearly is Maxwellian ( 1 keV) and the electron temperaturemeasured with SX-CCD camera is consistent with thatmeasured with YAG Thomson scattering. However, the highenergy electrons is observed in the energy range of> 2keV,when the electron density is below critical values(O.5x 1019m-3 in this experiment). The effective energy ofhigh energy electrons is 4 - 5 keY, which is much higherthan the temperature of bulk electrons measure with YAGThomson scattering.276

Measurement of Energy Spectrum of Electrons Using Photon Counting Soft X-ray CCD Camera

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Measurement of Energy Spectrum of Electrons Using Photon Counting Soft X-ray CCD Camera

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