First Operation of the TASCC Beam Bunching System

The Chalk River Tandem Accelerator Superconducting Cyclotron (TASCC) system uses a low-energy buncher (LER) and a high-energy rebuncher (HER) to prodtice the required bunched beam at the cyclotron injection stripper foil. The LEB modulates the < 300 keV beam from the negative ion source with a f¿undamental plus 2nd harmonic approximation to an ideal saw tooth to give a time focus at the stripper in the tandem accelerator terminal. The HEB, operating at the 2nd or 4th harmonic, corrects for debunching after the stripper and produces a new time focus at the cyclotron stripper. Transit time jitter through the tandem accelerator is corrected by a phase stabilizing circuit using both energy analysis after the HEB and a correlation with a capacitive phase probe signal . In the first experiments with a low energy 12C beam, the LEB produced bunch lengths of about 1.6 ns and the HEB produced the expected energy dispersion. Beam tests will be described.