| Paper | Title | Page |
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MOPA01 |
Large-Area Uniform Ion Beams Formed by Nonlinear Focusing with Multipole Magnets at the JAEA AVF Cyclotron Facility | |
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| Uniform irradiation with ion beams is a basic accelerator technique for various applications. At the AVF cyclotron facility in Japan Atomic Energy Agency, we have recently realized the formation of ion beams with a large-area (over 100 cm2) uniform intensity distribution by the nonlinear focusing force of multipole magnets for advanced research and future industrial applications. The uniform beam can be formed by the following procedure: First, a beam extracted from the cyclotron, which has a non-Gaussian, complicated profile, is smoothed out by multiple Coulomb scattering into a Gaussian-like one, which is prerequisite for the uniform-beam formation. Then, the tail of the beam is folded into the inside by the nonlinear focusing force of multipole magnets so that the distribution is made uniform on a target. The uniform beam is useful for the suppression of local target heating and efficient low-fluence irradiation in comparison with existing scanning irradiation. In the presentation, the principle of the uniform-beam formation, the beam tuning procedure, the beam profile measurement method, and application examples will be shown. | ||
| MOPA11 | Phase Bunching in the Central Region of the JAEA AVF Cyclotron for Heavy-Ion Acceleration in the Third-Harmonic Mode | 1 |
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| Phase bunching using a rising slope of a dee-voltage at the first acceleration gap was evaluated by analysis of a simplified geometric trajectory analysis model and the measurement of the internal beam phase distribution for the acceleration harmonic number (h) 3 to accelerate the heavy ion in the JAEA AVF cyclotron. The calculated correlation between the internal beam phase and the initial beam phase by the model was consistent with the measurement result of the beam phase distributions with the initial beam phase, defined by adjusting the relative RF phase of the beam buncher. The measured correlation indicated that the initial beam phase width larger than 60 RF degrees was compressed to less than 15 RF degrees, and the internal beam phase was independent of the initial beam phase. The phase bunching effect was almost equal to that for h = 2 with different geometric electrode from h = 3 in the central region. | ||