Development of a 165MHz RFQ Accelerator System for KBSI

by Junbae Bahng (Ph.D Candidate)

Wednesday May 31, 2017, 4:00 PM → 5:00 PM Asia/Seoul

201-4호Junbae (제1과학관)

In order to overcome the limitation of electrostatic accelerator, accelerator which uses RF power has been developed in 1920’s. The RF type accelerator i.e, Alvarez and Wideroe accelerators, requires bunching as longitudinal focusing to accelerate ion beam with adjustment of the idea. linear accelerators faced problems of diffi- culat manufacturing for short periodic length in low energy region. besides strong electric repulsive force by space charge effect appears in low energy region. so, an idea of adding pertubation on RF electrode quadrupole had been proposed to solve problem. The distinctive structure provides that beam are generated bunch with high capture and accelerated from few keV to few MeV with high transmission rate. KBSI has been developed a compact accelerator system for generation of fast neutron by 2.7 MeV/u of lithium beam with super-conducting electron cyclotron resonance ion source (SC-ECRIS). In order to successful acceleration lithium beam which is generated from ion source, an RFQ accelerator and its related RF system have been developed. The developed RFQ accelerator provide lithium ion beam from 12 keV/u to 500 keV/u with 98.88 % of high transmission rate at 165 MHz of operation frequency. The RFQ has 2.32 meter long and it is possible to operate with CW mode to high efficiency of experiment and imaging. In addition, RF power sys- tem has been developed to provide sufficient RF power into RFQ cavity. RF system which consists of LLRF system for control, 5 KW of SSPA as IPA, tetrode tube am- plifier as FPA,coaxial transmission line and circulator for protection from reflection power provides 100 kW at operation frequency with CW mode. In order to devel- opement of RFQ accelerator including RF system, we has designed that RFQ has stable operation with high transmission rate by studing of beam dynamics, RF anal- ysis, heat analysis and cooling design. In this dessertation, we discuss about design result of RFQ accelerator and RF system and performance test of these system in detail.

Thesis Advisor: Prof. Hwanbae Park