Beamlet deflection due to beamlet-beamlet interaction in a large-area multiaperture negative ion source for JT-60U

Kamada, Masaki; Hanada, M.; Ikeda, Yoshitaka; Grisham, L.; Jiang, Wei

doi:10.1063/1.2819333

Cited by 15 publications

(7 citation statements)

References 4 publications

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“…Should the kerbs not provide the correct steering, it will not be difficult or expensive to modify them. Kerbs are presently used in the JT60-U accelerators [40], where they are known as field shaping plates.…”

Section: Compensation For Interaction Between Beamletsmentioning

confidence: 99%

Physics design of the HNB accelerator for ITER

et al. 2015

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The physics design of the accelerator for the heating neutral beamline on ITER is now finished and this paper describes the considerations and choices which constitute the basis of this design. Equal acceleration gaps of 88 mm have been chosen to improve the voltage holding capability while keeping the beam divergence low. Kerbs (metallic plates around groups of apertures, attached to the downstream surface of the grids) are used to compensate for the beamlet–beamlet interaction and to point the beamlets in the right direction. A novel magnetic configuration is employed to compensate for the beamlet deflection caused by the electron suppression magnets in the extraction grid. A combination of long-range and short-range magnetic fields is used to reduce electron leakage between the grids and limit the transmitted electron power to below 800 kW.

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Section: Compensation For Interaction Between Beamletsmentioning

confidence: 99%

Physics design of the HNB accelerator for ITER

et al. 2015

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“…Inside an electrostatic accelerator, the position of grid apertures can influence the direction of the beamlets. Investigations on this aspect have been carried out in Germany by Spädtke et al [27,28], in the UK by Holmes et al [29], in Japan by the JAERI team [30][31][32][33] and by the NIFS team [34][35][36][37]. Analytical and numerical models, able to simulate the interaction between positive or negative ion beams due to the space charge, were introduced taking into account the boundary conditions corresponding to different experiments.…”

Section: Effect Of Aperture Offsetmentioning

confidence: 99%

Physics and engineering design of the accelerator and electron dump for SPIDER

et al. 2011

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The ITER Neutral Beam Test Facility (PRIMA) is planned to be built at Consorzio RFX (Padova, Italy). PRIMA includes two experimental devices: a full size ion source with low voltage extraction called SPIDER and a full size neutral beam injector at full beam power called MITICA. SPIDER is the first experimental device to be built and operated, aiming at testing the extraction of a negative ion beam (made of H − and in a later stage D − ions) from an ITER size ion source. The main requirements of this experiment are a H − / D − extracted current density larger than 355 / 285 A m −2 , an energy of 100 keV and a pulse duration of up to 3600 s. Several analytical and numerical codes have been used for the design optimization process, some of which are commercial codes, while some others were developed ad hoc. The codes are used to simulate the electrical fields (SLACCAD, BYPO, OPERA), the magnetic fields (OPERA, ANSYS, COMSOL, PERMAG), the beam aiming (OPERA, IRES), the pressure inside the accelerator (CONDUCT, STRIP), the stripping reactions and transmitted/dumped power (EAMCC), the operating temperature, stress and deformations (ALIGN, ANSYS) and the heat loads on the electron dump (EDAC, BACKSCAT). An integrated approach, taking into consideration at the same time physics and engineering aspects, has been adopted all along the design process. Particular care has been taken in investigating the many interactions between physics and engineering aspects of the experiment. According to the "robust design" philosophy, a comprehensive set of sensitivity analyses was performed, in order to investigate the influence of the design choices to the most relevant operating parameters. The design of the SPIDER accelerator, here described, has been developed in order to satisfy with reasonable margin all the requirements given by ITER, from the physics and engineering points of view. In particular, a new approach to the compensation of unwanted beam deflections inside the accelerator and a new concept for the Electron Dump have been introduced.

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“…6 The beamlet-beamlet interaction is observed in the negative ion source with a large-area accelerator. 18 The spacecharge repulsion force makes outer beamlets be deflected outward, and the deviation of the beamlet trajectory causes additional deflection at the downstream grid aperture. The simulation study reveals that outer three to four beamlets are deflected by the beamlet-beamlet interaction while trajectories of the inner beamlets are not influenced, as shown in Fig.…”

Section: Large-area Beam Accelerationmentioning

confidence: 99%

Negative ion source development for fusion application (invited)

Takeiri

2010

Review of Scientific Instruments

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Giant negative ion sources, producing high-current of several tens amps with high energy of several hundreds keV to 1 MeV, are required for a neutral beam injector ͑NBI͒ in a fusion device. The giant negative ion sources are cesium-seeded plasma sources, in which the negative ions are produced on the cesium-covered surface. Their characteristic features are discussed with the views of large-volume plasma production, large-area beam acceleration, and high-voltage dc holding. The international thermonuclear experimental reactor NBI employs a 1 MeV-40 A of deuterium negative ion source, and intensive development programs for the rf-driven source plasma production and the multistage electrostatic acceleration are in progress, including the long pulse operation for 3600 s. Present status of the development, as well as the achievements of the giant negative ion sources in the working injectors, is also summarized.

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Beamlet deflection due to beamlet-beamlet interaction in a large-area multiaperture negative ion source for JT-60U

Cited by 15 publications

References 4 publications

Physics design of the HNB accelerator for ITER

Physics design of the HNB accelerator for ITER

Physics and engineering design of the accelerator and electron dump for SPIDER

Negative ion source development for fusion application (invited)

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