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52. Overview of the RFX fusion science program

Author

Martin, P., primary, Adamek, J., additional, Agostinetti, P., additional, Agostini, M., additional, Alfier, A., additional, Angioni, C., additional, Antoni, V., additional, Apolloni, L., additional, Auriemma, F., additional, Barana, O., additional, Barison, S., additional, Baruzzo, M., additional, Bettini, P., additional, Boldrin, M., additional, Bolzonella, T., additional, Bonfiglio, D., additional, Bonomo, F., additional, Boozer, A.H., additional, Brombin, M., additional, Brotankova, J., additional, Buffa, A., additional, Canton, A., additional, Cappello, S., additional, Carraro, L., additional, Cavazzana, R., additional, Cavinato, M., additional, Chacon, L., additional, Chitarin, G., additional, Cooper, W.A., additional, Bello, S. Dal, additional, Dalla Palma, M., additional, Delogu, R., additional, De Lorenzi, A., additional, De Masi, G., additional, Dong, J.Q., additional, Drevlak, M., additional, Escande, D.F., additional, Fantini, F., additional, Fassina, A., additional, Fellin, F., additional, Ferro, A., additional, Fiameni, S., additional, Fiorentin, A., additional, Franz, P., additional, Gaio, E., additional, Garbet, X., additional, Gazza, E., additional, Giudicotti, L., additional, Gnesotto, F., additional, Gobbin, M., additional, Grando, L., additional, Guo, S.C., additional, Hirano, Y., additional, Hirshman, S.P., additional, Ide, S., additional, Igochine, V., additional, In, Y., additional, Innocente, P., additional, Kiyama, S., additional, Liu, S.F., additional, Liu, Y.Q., additional, Lòpez Bruna, D., additional, Lorenzini, R., additional, Luchetta, A., additional, Manduchi, G., additional, Mansfield, D.K., additional, Marchiori, G., additional, Marcuzzi, D., additional, Marrelli, L., additional, Martini, S., additional, Matsunaga, G., additional, Martines, E., additional, Mazzitelli, G., additional, McCollam, K., additional, Menmuir, S., additional, Milani, F., additional, Momo, B., additional, Moresco, M., additional, Munaretto, S., additional, Novello, L., additional, Okabayashi, M., additional, Ortolani, S., additional, Paccagnella, R., additional, Pasqualotto, R., additional, Pavei, M., additional, Perverezev, G.V., additional, Peruzzo, S., additional, Piovan, R., additional, Piovesan, P., additional, Piron, L., additional, Pizzimenti, A., additional, Pomaro, N., additional, Pomphrey, N., additional, Predebon, I., additional, Puiatti, M.E., additional, Rigato, V., additional, Rizzolo, A., additional, Rostagni, G., additional, Rubinacci, G., additional, Ruzzon, A., additional, Sakakita, H., additional, Sanchez, R., additional, Sarff, J.S., additional, Sattin, F., additional, Scaggion, A., additional, Scarin, P., additional, Schneider, W., additional, Serianni, G., additional, Sonato, P., additional, Spada, E., additional, Soppelsa, A., additional, Spagnolo, S., additional, Spolaore, M., additional, Spong, D.A., additional, Spizzo, G., additional, Takechi, M., additional, Taliercio, C., additional, Terranova, D., additional, Toigo, V., additional, Valisa, M., additional, Veranda, M., additional, Vianello, N., additional, Villone, F., additional, Wang, Z., additional, White, R.B., additional, Yadikin, D., additional, Zaccaria, P., additional, Zamengo, A., additional, Zanca, P., additional, Zaniol, B., additional, Zanotto, L., additional, Zilli, E., additional, Zollino, G., additional, and Zuin, M., additional

Published
2011
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55. On the statistics of edge fluctuations: comparative study between various fusion devices

Author

Sattin, F, primary, Agostini, M, additional, Scarin, P, additional, Vianello, N, additional, Cavazzana, R, additional, Marrelli, L, additional, Serianni, G, additional, Zweben, S J, additional, Maqueda, R J, additional, Yagi, Y, additional, Sakakita, H, additional, Koguchi, H, additional, Kiyama, S, additional, Hirano, Y, additional, and Terry, J L, additional

Published
2009
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59. Development of a strongly focusing high-intensity He+ ion source for a confined alpha particle measurement at ITER

Author

Kisaki, M., primary, Shinto, K., additional, Kobuchi, T., additional, Okamoto, A., additional, Kitajima, S., additional, Sasao, M., additional, Tsumori, K., additional, Nishiura, M., additional, Kaneko, O., additional, Matsuda, Y., additional, Wada, M., additional, Sakakita, H., additional, Kiyama, S., additional, and Hirano, Y., additional

Published
2008
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76. Investigation on the Characteristics of Pellet Ablation in a Toroidal Plasma.

Author

Sato, K. N., Sakakita, H., and Fujita, H.

Subjects
*TOKAMAKS, *PINCH effect (Physics), *FUSION reactors, *PLASMA gases
Abstract

Characteristics of a cloud ablated from an ice pellet has been investigated in detail in the JIPP T-IIU tokamak plasma by utilizing a new scheme of pellet injection system, "the injection-angle controllable system". A long "helical tail" of ablation light has been observed using CCD cameras and a high speed framing photograph in the case of on-axis and off-axis injection with the injection angle smaller than a certain value. The direction of the helical tail is found to be independent to that of the total magnetic field lines of the torus. From the experiments with the combination of two toroildal filed directions and two plasma current directions, it is considered that the tail seems to rotate, in most cases, to the electron diamagnetic direction poloidally, and to the opposite to the plasma current direction toroidally. Consideration on various cross sections including charge exchange, ionization and elastic collisions leads us to the conclusion that the tail-shaped phenomena may come from the situation of charge exchange equilibrium of hydrogen ions and neutrals at extremely high density regime in the cloud. The relation of ablation behavior with plasma potential and rotation has also been studied. Potential measurements of pellet-injected plasmas using heavy ion beam probe (HIBP) method were carried out for the first time. In the case of an injection angle to be anti-parallel to the electron diamagnetic direction in the poloidal plane, the result shows that the direction of potential change is negative, and consequently the potential after the injection should be negative because it has been measured to be negative in usual ohmic plasmas without pellet injection. Thus, the direction of the "tail" structure seems to be consistent to that of the plasma potential measured, if it is considered that tail structure may be caused by the effect of the plasma potential and the rotation. [ABSTRACT FROM AUTHOR]

Published
2003

79. Structural design and manufacturing of TPE-RX vacuum vessel

Author

Sago, H, primary, Orita, J, additional, Kaguchi, H, additional, Ishigami, Y, additional, Urata, K, additional, Kudough, F, additional, Hasegawa, M, additional, Oyabu, I, additional, Yagi, Y, additional, Sekine, S, additional, Shimada, T, additional, Hirano, Y, additional, Sakakita, H, additional, and Koguchi, H, additional

Published
1999
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80. The first results of TPE-RX, a large reversed-field pinch machine

Author

Yagi, Y, primary, Sakakita, H, additional, Shimada, T, additional, Hayase, K, additional, Hirano, Y, additional, Hirota, I, additional, Kiyama, S, additional, Koguchi, H, additional, Maejima, Y, additional, Osakabe, T, additional, Sato, Y, additional, Sekine, S, additional, and Sugisaki, K, additional

Published
1999
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81. Observation of dust particles by a laser scattering method in the JIPPT-IIU tokamak

Author

Narihara, K, primary, Toi, K, additional, Hamada, Y, additional, Yamauchi, K, additional, Adachi, K, additional, Yamada, I, additional, Sato, K.N, additional, Kawahata, K, additional, Nishizawa, A, additional, Ohdachi, S, additional, Sato, K, additional, Seki, T, additional, Watari, T, additional, Xu, J, additional, Ejiri, A, additional, Hirokura, S, additional, Ida, K, additional, Kawasumi, Y, additional, Kojima, M, additional, Sakakita, H, additional, Ido, T, additional, Kitachi, K, additional, Koog, J, additional, and Kuramotyo, H, additional

Published
1997
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82. Density fluctuations in JIPP T-IIU tokamak plasmas measured by a heavy ion beam probe

Author

Hamada, Y, primary, Nishizawa, A, additional, Kawasumi, Y, additional, Fujisawa, A, additional, Narihara, K, additional, Ida, K, additional, Ejiri, A, additional, Ohdachi, S, additional, Kawahata, K, additional, Toi, K, additional, Sato, K, additional, Seki, T, additional, Iguchi, H, additional, Adachi, K, additional, Hidekuma, S, additional, Hirokura, S, additional, Iwasaki, K, additional, Ido, T, additional, Kojima, M, additional, Koong, J, additional, Kumazawa, R, additional, Kuramoto, H, additional, Minami, T, additional, Nomura, I, additional, Sakakita, H, additional, Sasao, M, additional, Sato, K.N, additional, Tsuzuki, T, additional, Xu, J, additional, Yamada, I, additional, and Watari, T, additional

Published
1997
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83. Measurement of ablation cloud parameters and plasma potential with on/off-axis pellet injection in the JIPP T-IIU tokamak

Author

Sakakita, H, primary, Sato, K.N, additional, Nomura, I, additional, Hamada, Y, additional, Nishizawa, A, additional, Kawasumi, Y, additional, Ida, K, additional, Xu, J, additional, Narihara, K, additional, Toi, K, additional, Ejiri, A, additional, Seki, T, additional, Adachi, K, additional, Iguchi, H, additional, Fujisawa, A, additional, Liang, R, additional, Sakamoto, M, additional, Kano, Y, additional, Hirokura, S, additional, Hidekuma, S, additional, and Kojima, M, additional

Published
1997
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85. Large potential change induced by pellet injection in JIPP T-IIU tokamak plasmas

Author

Hamada, Y, primary, Sato, K.N, additional, Sakakita, H, additional, Nishizawa, A, additional, Kawasumi, Y, additional, Liang, R, additional, Kawahata, K, additional, Ejiri, A, additional, Toi, K, additional, Narihara, K, additional, Sato, K, additional, Seki, T, additional, Iguchi, H, additional, Fujisawa, A, additional, Adachi, K, additional, Hidekuma, S, additional, Hirokura, S, additional, Ida, K, additional, Kojima, M, additional, Koong, J, additional, Kumazawa, R, additional, Kuramoto, H, additional, Minami, T, additional, Sasao, M, additional, Tsuzuki, T, additional, Xu, J, additional, Yamada, I, additional, and Watari, T, additional

Published
1996
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86. Fast potential change during sawteeth in JIPP T-IIU tokamak plasmas

Author

Hamada, Y, primary, Nishizawa, A, additional, Kawasumi, Y, additional, Kawahata, K, additional, Itoh, K, additional, Ejiri, A, additional, Toi, K, additional, Narihara, K, additional, Sato, K, additional, Seki, T, additional, Iguchi, H, additional, Fujisawa, A, additional, Adachi, K, additional, Hidekuma, S, additional, Hirokura, S, additional, Ida, K, additional, Kojima, M, additional, Koong, J, additional, Kumazawa, R, additional, Kuramoto, H, additional, Liang, R, additional, Minami, T, additional, Sakakita, H, additional, Sasao, M, additional, Sato, K.N, additional, Tsuzuki, T, additional, Xu, J, additional, Yamada, I, additional, and Watari, T, additional

Published
1996
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87. Characteristics of pellet injected discharges in TEXTOR

Author

Finken, K. H., primary, Sato, K. N., additional, Akiyama, H., additional, Fuchs, G., additional, Jaspers, R., additional, Kogoshi, S., additional, Koslowski, H. R., additional, Mank, G., additional, Sakakita, H., additional, Sakamoto, M., additional, Sander, M., additional, and Soltwisch, H., additional

Published
1995
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88. Improvement of a 500 keV heavy-ion-beam probe for JIPP T-IIU tokamak

Author

Hamada, Y., primary, Kawasumi, Y., additional, Nishizawa, A., additional, Narihara, K., additional, Sato, K., additional, Seki, T., additional, Toi, K., additional, Iguchi, H., additional, Fujisawa, A., additional, Adachi, K., additional, Ejiri, A., additional, Hidekuma, S., additional, Hirokura, S., additional, Ida, K., additional, Kawahata, K., additional, Kojima, M., additional, Joong, K., additional, Kumazawa, R., additional, Kuramoto, H., additional, Liang, R., additional, Minami, T., additional, Sakakita, H., additional, Sasao, M., additional, Sato, K. N., additional, Tsuzuki, T., additional, Xu, J., additional, Yamada, I., additional, and Watari, T., additional

Published
1995
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89. Measurement of profiles of the space potential in JIPP T-IIU tokamak plasmas by slow poloidal and fast toroidal sweeps of a heavy ion beam

Author

Hamada, Y, primary, Nishizawa, A, additional, Kawasumi, Y, additional, Narihara, K, additional, Sato, K, additional, Seki, T, additional, Toi, K, additional, Iguchi, H, additional, Fujisawa, A, additional, Adachi, K, additional, Ejiri, A, additional, Hidekuma, S, additional, Hirokura, S, additional, Ida, K, additional, Koong, J, additional, Kawahata, K, additional, Kojima, M, additional, Kumazawa, R, additional, Huramoto, H, additional, Liang, R, additional, Sakakita, H, additional, Sasao, M, additional, Sato, K N, additional, Tsuzuki, T, additional, Xu, J, additional, Yamada, I, additional, Watari, T, additional, and Negi, I, additional

Published
1994
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90. Effects of a dielectric material in an ion source on the ion beam current density and ion beam energy.

Author

Fujiwara, Y., Sakakita, H., Nakamiya, A., Hirano, Y., and Kiyama, S.

Subjects
*DIELECTRIC materials, *ION sources, *ION beams, *HYDROGEN ions, *ELECTRODES, *ELECTRON density
Abstract

To understand a strong focusing phenomenon that occurs in a low-energy hydrogen ion beam, the electron temperature, the electron density, and the space potential in an ion source with cusped magnetic fields are measured before and after the transition to the focusing state using an electrostatic probe. The experimental results show that no significant changes are observed before or after the transition. However, we found unique phenomena that are characterized by the position of the electrostatic probe in the ion source chamber. Specifically, the extracted ion beam current density and energy are obviously enhanced in the case where the electrostatic probe, which is covered by a dielectric material, is placed close to an acceleration electrode. [ABSTRACT FROM AUTHOR]

Published
2016
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91. Spectroscopic system using image magnifying optics for plasma velocity and ion temperature measurement.

Author

Sakakita, H., Kiyama, S., Hirano, Y., Yagi, Y., Koguchi, H., Sekine, S., Shimada, T., Hirota, I., and Maejima, Y.

Subjects
*SPECTROSCOPIC imaging, *PLASMA gases, *IONS, *TEMPERATURE measurements, *SCIENTIFIC apparatus & instruments
Abstract

A spectroscopic system equipped with image magnifying optics has been developed for measuring a time-resolved plasma velocity at one discharge of a reversed-field-pinch plasma of the TPE-RX at National Institute of AIST. This spectroscopic system enables a simultaneous measurement from two different lines of sight, using two sets of quartz optical fiber bundles. This system provides a precise measurement of Doppler shift without the need for a calibration of the central location of a spectral line. Two fiber bundles are coupled to the entrance slit of a modified Czemy-Turner-type, 1-m-focal-length spectrometer with an 82 × 82 mm² grating. In order to adjust the spectral image of the exit slit to each surface of two sets of one-dimensional detector arrays, an optical system equipped with a toroidal mirror, a cylindrical mirror, and splitting mirrors has been developed. The focal lengths of the toroidal mirror are selected for focusing vertically on the splitting mirror and horizontally (wavelength direction) on detectors. Plasma rotation and ion temperature for O v impurity ions (278.1 nm) are successfully measured at one plasma shot with a 25-µs time resolution in the TPE-RX. [ABSTRACT FROM AUTHOR]

Published
2003
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92. Overview of diagnostics system for the TPE-RX reversed-field pinch.

Author

Yagi, Y., Koguchi, H., Sekine, S., Sakakita, H., Hirano, Y., Shimada, T., Canton, A., and Innocente, P.

Subjects
REVERSED field pinches, SCIENTIFIC apparatus & instruments
Abstract

An overview of the present diagnostics system for a reversed-field pinch machine, the toroidal pinch experiment RX [TPE-RX, R/a = 1.72/0.45 m, I[sub p] < 1 MA (designed)], is presented. The diagnostic system of TPE-RX consists of measurement systems for (1) equilibrium configuration, (2) perturbing modes, and (3) global confinement properties. A concise explanation is given for these diagnostics systems. The mode-measurement system, in particular, is equipped with high toroidal resolution (up to the mode number of 32), which is necessary for the reversed-field pinch configuration. We have magnetic, thermal, and spectroscopic measurement systems for the toroidal distribution of the perturbing modes, which are useful for revealing the mode-locking structure. [ABSTRACT FROM AUTHOR]

Published
2003
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93. Data acquisition and analysis system for the TPE-RX reversed-field pinch.

Author

Koguchi, H., Yagi, Y., Hirano, Y., Shimada, T., Sakakita, H., and Sekine, S.

Subjects
REVERSED field pinches, SPECTROSCOPIC imaging, SCIENTIFIC apparatus & instruments
Abstract

Data acquisition and analysis systems for a reversed-field pinch (RFP) machine, the toroidal pinch experiment (RX) [TPE-RX, R/a = 1.72/0.45 m, I[sub p] < 1 MA (designed)], are presented. Many kinds of diagnostic systems are installed on TPE-RX, and 392 signal channels at maximum from the diagnostic systems are routinely acquired by using the Computer Automated Measurement and Control system. The data are acquired through a serial highway into a front-end computer. A custom made, special computer program system, called DAQR, has been developed for the data acquisition routine. Software libraries are also developed for the data analyses of the plasma parameters, perturbed mode structures of the RFP plasma, and radiation from plasma. [ABSTRACT FROM AUTHOR]

Published
2003
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94. Self-focusing of a high current density ion beam extracted with concave electrodes in a low energy region around 150 eV.

Author

Hirano, Y., Kiyama, S., Koguchi, H., and Sakakita, H.

Subjects
ION beams, HYDROGEN ions, ELECTRIC resistors, ELECTIONS, ELECTRODES
Abstract

Spontaneous self-focusing of ion beam with high current density (Jc ~ 2 mA/cm², Ib ~ 65 mA) in low energy region (~150 eV) is observed in a hydrogen ion beam extracted from an ordinary bucket type ion source with three electrodes having concave shape (acceleration, deceleration, and grounded electrodes). The focusing appears abruptly in the beam energy region over ~135-150 eV, and the Jc jumps up from 0.7 to 2 mA/cm². Simultaneously a strong electron flow also appears in the beam region. The electron flow has almost the same current density. Probably these electrons compensate the ion space charge and suppress the beam divergence. [ABSTRACT FROM AUTHOR]

Published
2014
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95. Effects of filament geometry on the arc efficiency of a high-intensity He+ ion source.

Author

Kobuchi, T., Kisaki, M., Shinto, K., Okamoto, A., Kitajima, S., Sasao, M., Tsumori, K., Kaneko, O., Sakakita, H., Kiyama, S., Hirano, Y., and Wada, M.

Subjects
ION sources, ELECTRODES, ALPHA rays, FUSION (Phase transformation), PLASMA gases, HELIUM
Abstract

A strongly focusing high-intensity He+ ion source equipped with three concave electrodes has been designed and constructed as the beam source for a high-energy He0 neutral beam probe system to diagnose fusion-produced alpha particles in thermonuclear fusion plasmas. The reduction of heat load onto the concave extraction electrodes is particularly important for a long pulse operation, as the heat load deforms the electrodes and thus the beam focal length. The effects on the arc efficiency (beam current/arc power) of the ion source due to the discharge filament structure (straight-type and L-shape-type filaments), size (filament diameters of 2 and 1.5 mm), number, and the locations have been studied. Choice of the appropriate filament structure improved the arc efficiency by 17%. [ABSTRACT FROM AUTHOR]

Published
2008
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96. Development of a strongly focusing high-intensity He+ ion source for a confined alpha particle measurement at ITER.

Author

Kisaki, M., Shinto, K., Kobuchi, T., Okamoto, A., Kitajima, S., Sasao, M., Tsumori, K., Nishiura, M., Kaneko, O., Matsuda, Y., Wada, M., Sakakita, H., Kiyama, S., and Hirano, Y.

Subjects
ION sources, NUCLEAR physics instruments, ELECTRON cyclotron resonance sources, IONS, SCIENTIFIC apparatus & instruments
Abstract

A strongly focusing high-intensity He+ ion source has been designed and constructed as a beam source for a high-energy He0 beam probe system for diagnosis of fusion produced alpha particles in the thermonuclear fusion plasmas. The He+ beam was extracted from the ion source at an acceleration voltage of 18–35 kV. Temperature distributions of the beam target were observed with an IR camera. The 1/e-holding beam profile half-width was about 15 mm at optimum perveance (Perv) of 0.03 (Ibeam=2.4 A). A beam current about 3 A was achieved at an acceleration voltage of 26.7 kV with an arc power of 10 kW (Perv=0.023). [ABSTRACT FROM AUTHOR]

Published
2008
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97. Soft x-ray tomography system for the toroidal pinch experiment-RX reversed-field pinch.

Author

Koguchi, H., Shimada, T., Asai, T., Yagi, Y., Hirano, Y., and Sakakita, H.

Subjects
X-rays, TOMOGRAPHY, DETECTORS, MAGNETOHYDRODYNAMICS, PLASMA gases, PLASMA dynamics
Abstract

A soft x-ray (SXR) measurement system for tomography analysis on a reversed-field pinch machine. torodial pinch experiment, RX [TPE-RX, R/a=1.72/0.45 m, Ip<1 MA (designed)], is presented. The soft x-ray imaging system consists of two surface barrier detector (SBD) arrays that are vertical and horizontal. Thirteen SBDs are installed on the vertical ports and used for the measurement along vertical lines of sight. Eleven SBDs are installed on the horizontal port and used for the measurement along a fan-shaped line of sight. These detectors have 15-μm-thick Be foil with sensitivity in the soft x-ray range. This system is installed in order to study the structure of the SXR emission from the plasma core and to know the relation between global performance and magnetohydrodynamics dynamics. This system has been used under several operating conditions in addition to those of standard operation. The first results of these experiments are reported. [ABSTRACT FROM AUTHOR]

Published
2004
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98. Optical and electrical diagnostics for the investigation of edge turbulence in fusion plasmas.

Author

Cavazzana, R., Scarin, P., Serianni, G., Agostini, M., Degli Agostini, F., Cervaro, V., Lotto, L., Yagi, Y., Sakakita, H., Koguchi, H., and Hirano, Y.

Subjects
PLASMA turbulence, PLASMA frequencies, DETECTORS, TURBULENCE, PLASMA gases, CALIBRATION
Abstract

A new, two dimensional and fast diagnostic system has been developed for studying the dynamic structure of plasma turbulence; it will be used in the edge of the reversed-field pinch devices TPE-RX and RFX. The system consists of a gas-puffing nozzle, 32 optical channels measuring Hα emitted from the puffed gas (to study the optical emissivity of turbulent patterns and to analyze structures in two dimensions), and an array of Langmuir probes (to compare the turbulent pattern with the optical method and to measure the local plasma parameters). The signals can be acquired at 10 Msamples/s with 2 MHz band width. The design of the system, calibrations, and tests of the electronic circuitry and the optical sensors are presented. [ABSTRACT FROM AUTHOR]

Published
2004
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