Upgrade of the analyzer design for multipoint measurements by a gold neutral beam probe on the GAMMA 10 tandem mirror

Abstract

The study of the mechanisms of both transport and fluctuations is one of the main issues of fusion plasma researches. Spatial fluctuation structure measurements are important for studying of cross correlation between the two fluctuations. Gold neutral beam probe systems are used in GAMMA 10 tandem mirror plasma device. Currently, the plasma potential and its fluctuations cannot be measured at different radial positions simultaneously. This paper presents the upgrade design of the 45 degrees electrostatic energy analyzer for the simultaneous multipoint measurements of plasma parameters.

Simultaneous evaluation of potential fluctuation from the core plasma to the end region in GAMMA 10

“…GAMMA 10 is an effectively axisymmetrized minimum-B anchored tandem mirror with thermal barriers at both end mirrors (figure 1). It is described in detail elsewhere [6][7][8][9][10][11][12][13][14][21][22][23][24][25]. The x-axis and y-axis are perpendicular to the magnetic field in the vertical and horizontal directions, respectively.…”

“…We used the heavy ion beam probe to measure the potential of the core plasma in the central cell of GAMMA 10 [12,[21][22][23][24][25]]. We measured the potential and its fluctuations using the GNBP in the central cell (z = 1.18 m) (figure 2).…”

“…GAMMA 10 has a good potential measurement system consisting of a gold neutral beam probe (GNBP) system [12,[21][22][23][24][25]. We can observe the density and potential fluctuations when the axial confinement potential is formed during the application of P/B-ECH in a single plasma shot.…”

“…However, the earlier study could obtain only the potential and electric field at different times in the same plasma shot. Thus, we developed the twopoint potential measurement GNBP system by changing the incident slit to a double-slit configuration in the GNBP analyser [22,24]. This enables a more detailed study of the suppression mechanisms of drift-type fluctuations during the formation of a confinement potential produced by P-ECH.…”

Suppression of flute-like fluctuation by potential formation in GAMMA 10/PDX

“…The density fluctuation is observed using microwaves, such as the interferometer, reflectometry and Fraunhofer diffraction method, and electrostatic probes [1][2][3]5,6]. The potential fluctuation is observed by the gold neutral beam probe (GNBP) and the end plates [4,[15][16][17][18][19]. In the former experiments, we studied the drift-type fluctuation suppression by applying the P-ECH [5,6,[15][16][17][18][19].…”