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beam dynamics in J-PARC LEBTShibata, Takanori*; Ikegami, Kiyoshi*; Liu, Y.*; Miura, Akihiko; Naito, Fujio*; Nammo, Kesao*; Oguri, Hidetomo; Okoshi, Kiyonori; Otani, Masashi*; Shinto, Katsuhiro; et al.
Proceedings of 29th International Linear Accelerator Conference (LINAC 2018) (Internet), p.519 - 521, 2019/01
Transport process of negative hydrogen ion (H) in LEBT (Low Energy Beam Transport) is investigated by comparison of experimental and numerical results. A three dimensional Particle-In-Cell (PIC) particle transport model has been developed in order to take into account (i) axial magnetic field by two solenoids in J-PARC LEBT and (ii) radial electric field by space charge (SC) effect. Ratio of H
beam particles inside the RFQ (Radio Frequency Quadrupole) acceptance to the total particles at the RFQ entrance is calculated for different current conditions in LEBT solenoid 1 and 2. The results are compared with RFQ transmission rate measured in the J-PARC linac commissioning. The double peak of RFQ transmission rate to the solenoid applied current seen in the measurement is explained by the calculation results. The results indicate that presence of the LEBT orifice for differential pumping plays a role as a collimator to reduce emittance at RFQ entrance.
Agematsu, Takashi; Arakawa, Kazuo; *
Cyclotrons and Their Applications 1998 (Cyclotrons'98), p.232 - 235, 1998/00
no abstracts in English
Fuwa, Yasuhiro; Moriya, Katsuhiro; Takayanagi, Tomohiro
no journal, ,
In the high-intensity operation of the J-PARC Linac, it is necessary to suppress the beam loss caused by the emittance growth and the beam halo formation due to the space charge in the low-energy region. As a method to suppress the space charge effect, it has been proposed to cancel the effect of higher-order components of the space charge effect by using higher-order multipole fields such as octupole fields. In this presentation, we will report the characteristics of the multipole magnets fabricated for the MEBT1 of the J-PARC Linac and simulation results on the suppression of the space charge effect based on the magnetic field distribution generated by the fabricated magnet.
