In order to expend the upper limit of beam LET,the technology of ~(238)U target cone preparation,ion source extracting and high charge state~(238)U ion extracting at the target chamber has been studied in the HI-13 tandem accelerator.Different compounds in the form of ~(238)U material corresponding to the ion source extracting beam current In order to expend the upper limit of beam LET, the technology of ~ (238) U target cone preparation, ion source extracting and high charge state ~ (238) U ion extraction at the target chamber has been studied in the HI-13 tandem accelerator. Different compounds in the form of ~ (238) U material corresponding to the ion source extract beam current