THE STUDY ON CCDTL STRUCTURE

The CCDTL (Coupled Cavity Drift Tube Linac) structure presented by Los Alamos Lab is a new structure for proton's velocity from 0.1c to 0.5c. The CCDTL aluminium and copper model are manufactured. The final OFHC (Oxygen Free High Conductivity) model consists of four accelerating cavities and three coupling cavities. There only is one drift tube in the accelerating cavity, so one accelerating cavity has two accelerating gaps. The model was made and tuned. The basic characteristics of the structure such as cavity frequency, dispersion curve, coupling, field profile are measured. 1 INTRODUTION The CCDTL concept was invented in 1994[1]. Then it plays a major role in the APT Low-Energy Linac (LEL) design. In China, we want to design our intense proton beam accelerator. We plan to research the CCDTL due to its merits. Since 1998, we have got the support fund from National Natural Science Foundation of China. First the cold aluminium model was made. The coupling slot influence was measured. And the relationship between coupling k1 and coupling slot area was simply tested. Then an OFHC copper cold model was designed and made. The basic technological machine steps and design steps were explored. By the help of experience in tuning SSC CCL modules, we are tuning the OFHC copper cavity. Before the model study on CCDTL, the symmetrical design of the CCDTL is explored[2]. Because of the basis of using computer simulation on the beam dynamic is poor, the research work is not continued. In the process of research, we got the news from the international conference. In new intense proton beam accelerator project, the Los Alamos scientist did not choose the CCDTL structure. The reason was not published. It is said that in the high power test, the CCDTL structure did not work stable. But we think that the CCDTL will be used in the weak beam, low duty factor conditions.