R. Kumazawa

Y. Torii

National Institute for Fusion Science (NIFS-Repository)

§ 16. High Energy Ion Component Measurement by ICRF Power Modulation Method Torii, Y. (Nagoya Univ.), Kumazawa, R. As the confinement time of high energy ions is much different between in Rax=3.6m and in Rax=3.75m, a different ratio of the stored energy of the high energy ions to that of the bulk plasma can be experimentally observed. An analysis in the plasma discharge with the RF power modulation gives the tail fraction of high energy ions by measuring phase difference among the total stored energy OWp, the bulk plasma stored energy OWb and the ICRF heating power oP A' The relations between OWp and OWb and between oP A and OWp are reri ved from the power balance equation and expressed in the following complex equations, OWp = 1 + i A~b + i i cor 12 ~ 2 11rms 2 seO ' 3 . A~b ow: 1 + -(zcorseO 1 2 +-) p - 11 'l' 1211 2 11rms l5P - rms seO 0 AR ' A -B~b + (im11rms'l'seO 12 + l)(icorseO 12 + _rb) 11rms 'l'rail 3 11' To 3 ~b =_E_, A =-2 +(1- {3), B=-+-2' 'l'E 110 Here the energy transfer from the high energy ions to helium ions is neglected. Rtb is a ratio of the stored energy of the high energy ions to that of the bulk plasma co and ~ are an applied modulation frequency and a numerical factor rerived from the repenrence of the energy confinement time on the temperature, i.e., 'rE ex: 'rEoTf3; 13=-1.44 rerived from ISS95. 110 is a heating efficiency and 1]' is its rerivative of temperature!). The phase difference epb between OWp and OWb, and the phase difference epA between OWp and oP A are given in the following equations; lw tanepb=~' l+ __ rb 11rms 333 (A + - B)~b + 1 + -(Al\b)2 + - W2 tan epA = - w A 2 3 Al\ 2 3 2 ,W = corJ 2. (- - B)(l + __ b )l\b + (- - 11rrns)W2 11rms 2 11rms 2 A relation between epA and e pb is obtained in the following equation by substituting tanepb instead of co't/2; 8 2 8 Al\b tan pA = --tan pb(l + --) 3 11rms x A 3 Al\b 3 2 Al\b 2' (- - B)(l + --)l\b + (- -11rrns)(-tan8pb (l + -)) 11lms 2 11rrns 2 3 11lms epA was calculated as a function of Rtb at five different e pb' epb=IO°, 15°, 20°, 25°, and 30° and plotted in Fig.I. epA increases with Rtb when Rtb < 0.2, reaches its maximum at Rtb = 0.2 and dxreases with Rtb at e pb=10°. epb oopends on co't/2; it increases with Te and with recrease in ne' The relation between epA and e pb is calculated as a parameter of Rtb. Loci of Rtb of 0.01, 0.1, 1.0 and 10.0 are plotted in the plane of e pb and epA as shown in Fig.2. It should be noted that the pressure ratio of Rtb can be reduced from the measurement of epA and epb' -40 r----r--..,....--.--,--.,..-__ -..,.... ...... -50 -80 -90 ~ ....... ~~_-~-_~~ ...... ~ o 1 2 R tb Fig.1 Dependence of a phase difference between Wp and P A on the pressure ratio of Rtb as the parameter of epb ' -. -30 en Q) Q) C» Q) '0 ~ a. CD -60 30 60 90 8pb (degrees) Fig.2 Dependence of a phase difference between Wp and P A on a phase difference between Wp and Wb as the parameter of the pressure ratio of Rtb. Reference 1) Y. Torii, et. al., Plasma Physics and controlled Fusion, 43 (2001) 1191. 129 

High Energy Ion Component Measurement by ICRF Power Modulation Method

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