Strong Cyclotron Axial Injection Deflector Beam Optical Characteristics And Design Methods

Since the cyclotron laboratory of CIAE (CHINA INSTITUTE OF ATOMIC ENERGY) is being devoted to the study of cyclotron design, they have undertaken a lot of practice and accumulated much experience in theory design and engineering. As we know, spiral inflector is an important part of the cyclotron injection system. Based on the study carried on in Belgium and financed by the scientific study funds of the nuclear industry, the cyclotron laboratory of CIAE has successfully designed the spiral inflector suitable for the 30MeV cyclotron magnet. Nonetheless, as the distance between two electrode boards of the inflector is fixed and its structure is fairly simple, there is no further study on the optical property, space charge effects and transferring property.At present the cyclotron development in CIAE is oriented in the field of intense current cyclotron. Either the experiment device in the central region of the intense current cyclotron or the lOOMeV cyclotron in the upgrading project of the tandem accelerator requires a magnetic filed different from that of the 30MeV cyclotron. As a result, a new spiral inflector needs to be designed. Meanwhile, as regards the compact intense current cyclotron, the study should be focused on the cooperation between the optical property and other elements injected into the transfer line when the rest phase space of the central region is fixed. Therefore, the matching between the optical property of the injected beam and the central region is crucial to increase the intensity of the beam in a cyclotron of this type. As the beam intensity increases, the interaction among the particles inside the beam and between the beams will make an increasing impact on the particles. Particularly, when the beam energy is fairly low, the spiral inflector is the main part of beam loss. As a consequence, it is of great significance to put in more time and energy on the study of the optical property of the spiral inflector and the space charge effects, which will accordingly improve the beam quality, reduce beam loss and increase the transferring efficiency in a 100MeV intense current cyclotron of the tandem upgrading project.Based on the problems mentioned above, this essay offers a detailed illustration on the optical property, space charge effects and transferring property of the spiral static inflector. Till now, we have finished independently the design of the spiral inflector of the experiment device in the central region and grasped some rules concerning the optical property of the inflector. Moreover, the influence on beam transfer of the spiral inflector caused by beams of different intensities is calculated out by modifying the source program that is applied to calculate the inflector. Though TRACE3D have been used in the optic matching design of many intense current beam transfer systems, it cannot handle with the special optic element like the spiral static inflector. Therefore, we add the transfer matrix of the spiral inflector to TRACE3D to make it match the optical property from the exit through which the ion source is extracted to the exit of the spiral inflector. In this way, the parameter of each element injected into the transferring line is modified and the beam injection is optimized. As a result, the transmission efficiency is improved and beam loss in the central region is reduced.The calculation and conclusion illustrated in this essay supply references to the design of the spiral inflector and meanwhile offer a good way for beam matching.