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21 results on '"Akiyama R"'

4. Recovery of cesium in the hydrogen negative ion sources

Author

Belchenko, Yu. I., primary, Oka, Y., additional, Kaneko, O., additional, Takeiri, Y., additional, Krivenko, A. S., additional, Osakabe, M., additional, Tsumori, K., additional, Asano, E., additional, Kawamoto, T., additional, and Akiyama, R., additional

Published
2000
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9. Energetic negative ion source for fusion at NIFS (invited)

Author

Kuroda, T., primary, Kaneko, O., additional, Takeiri, Y., additional, Oka, Y., additional, Tsumori, K., additional, Asano, E., additional, Kawamoto, T., additional, Akiyama, R., additional, Ando, A., additional, Takanashi, T., additional, and Hamabe, M., additional

Published
1996
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19. Development of fast response calorimeter for neutral beam shine-through measurement on CHS.

Author

Osakabe, M., Takeiri, Y., Takanashi, T., Tsumori, K., Okamura, S., Matsuoka, K., Akiyama, R., Asano, E., Kaneko, O., Kawamoto, Y., and Oka, T.

Subjects
CALORIMETERS, NEUTRAL beams, MEASUREMENT
Abstract

A fast response calorimeter has been developed for the neutral-beam (NB) shine-through measurement. This calorimeter has the following advantages. (1) Temporal variation of the heat load onto the calorimeter can be measured. (2) Measurement under the relatively high heat flux environment is possible. (3) The calorimetric measurement under continuous and steady-state heat load environment is also possible. The verification of the measurement principle was done using an NB-injection system on the compact helical system (CHS) at the National Institute for Fusion Science (NIFS). The measured NB power densities are compared to the power densities being evaluated by the CHS-NB profile database. It was experimentally confirmed that the time constant of the measurement is about 7 ms. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2001

20. In situ calibration of neutral beam port-through power and estimation of neutral beam deposition on LHD.

Author

Osakabe, M., Takeiri, Y., Tsumori, K., Murakami, S., Kaneko, O., Ikeda, K., Oka, Y., Asano, E., Kawamoto, T., Akiyama, R., Kawahata, K., Komori, A., Inoue, N., Yonezu, Y., Ohyabu, N., and Motojima, O.

Subjects
NEUTRAL beams, BEAM emittance (Nuclear physics), NUCLEAR physics
Abstract

The neutral beam (NB) shine-through profile is routinely monitored on the Large Helical Device (LHD) both to calibrate the port-through power of the NB and to evaluate the NB-deposition power to LHD plasmas. The profile is measured with a calorimeter (CM) array on an armor plate of the NB counter wall inside the LHD vacuum vessel. An infrared camera is also used to check the beam profile where CMs are not located, and measures a temperature increase of the armor plate due to the NB heat load. The measured beam profile is compared to the calculated NB profile at the armor plate. The measurement indicates that the beam is not uniform at the exit of the ion source and that the steering angle of the beam in the horizontal direction is not the same as the designed value. It is found that the monitoring of the NB shine-through profile is important to estimate the NB port-through power and the NB deposition power, especially when the neutral beam injector (NBI) is based on a large negative-hydrogen ion source. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2001

21. Loss cone boundary measurement using diagnostic neutral beam and neutral particle analyzer in a compact helical system.

Author

Matsushita, H., Ida, K., Okamura, S., Isobe, M., Akiyama, R., and Yoshimura, Y.

Subjects
NEUTRAL beams, IONS, CHARGE exchange, PLASMA gases, PARTICLES (Nuclear physics), PARTICLE beams
Abstract

A horizontally scannable diagnostic neutral beam (DNB) has been installed on the compact helical system (CHS) in order to study the confinement of energetic ions with different pitch angles by varying the injection angle. The DNB has been designed to provide energetic ions as a test particle source with (1) no heating to background plasma and (2) small divergence angle. A charge-exchange neutral particle analyzer (NPA) to measure energetic ions injected by the DNB is also scannable and varies the observation angle on the equatorial plane in CHS. A combination of horizontally scannable DNB and NPA provides information on whether the energetic ions with different pitch angle are confined in the plasma or immediately lost. The experimental results are consistent with the prediction of single particle full orbit calculation in CHS. [ABSTRACT FROM AUTHOR]

Published
2004
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