Formation of a large-area uniform ion beam using multipole magnets in the TIARA cyclotron
Formation of a large-area uniform ion beam using multipole magnets in the TIARA cyclotron
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DOI：
10.1016/j.nima.2011.03.055
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发表时间：
2011-06
影响因子：
1.4
通讯作者：
Y. Yuri;T. Ishizaka;T. Yuyama;I. Ishibori;S. Okumura;KEN-ICHI Yoshida
中科院分区：
文献类型：
--
作者：
Y. Yuri;T. Ishizaka;T. Yuyama;I. Ishibori;S. Okumura;KEN-ICHI Yoshida
日本原子能机构变方位场回旋加速器装置研究了基于非线性聚焦方法形成横向强度分布均匀的离子束。该方法使我们能够在大样品的整个区域上以恒定的粒子注量率进行均匀照射。为了在目标上获得大面积高度均匀的光束，我们首先通过多重散射平滑来自回旋加速器的光束的强度分布，然后使用八极磁铁聚焦平滑的光束。讨论了一种以小能量损失增强散射效应的有效技术。通过在八极聚焦之前准直平滑光束的尾部，可以在目标上获得具有几乎均匀轮廓的光束。此外，我们还表明，通过添加六极聚焦，可以将未对准的光束转变为均匀的光束。超短时间和超低通量照射的可能性已在材料和生物科学的高级应用中得到证明。与其他传统方法相比，从均匀照射方法的角度讨论了非线性聚焦方法产生的均匀光束的特性。
The formation of an ion beam with a uniform transverse intensity distribution based on anonlinear focusing methodhas been studied at the azimuthally varying field cyclotron facility of Japan Atomic Energy Agency. The method enables us to perform uniform irradiation at a constant particle fluence rate over the whole area of a large sample. To obtain a large-area highly uniform beam on the target, we first smooth the intensity distribution of the beam from the cyclotron by multiple scattering and then focus the smoothed beam using octupole magnets. An efficient technique to enhance the scattering effect with a small energy loss is discussed. By collimating the tail of the smoothed beam before octupole focusing, a beam with a nearly uniform profile can be attained on the target. Moreover, we also show that a misaligned beam can be transformed into a uniform beam by adding sextupole focusing. The possibility of ultra-short-time and ultra-low-fluence irradiation has been demonstrated toward advanced applications in materials and biological science. The characteristics of the uniform beam produced by the nonlinear focusing method are discussed from the viewpoint of a uniform irradiation method as compared to other conventional methods.