Initial operating experience with the auxiliary accelerating cavity for the TRIUMF cyclotron

A 92-MHz auxiliary accelerating cavity has been installed in the TRIUMF cyclotron. The cavity operates at the fourth harmonic of the main RF frequency with a planned peak voltage of 150 kV. At full power it will almost double the present energy gain per turn in the 400-500 MeV range, reducing by 25% the stripping loss of the H/sup -/ beam. Low-current beam tests have been conducted at voltages of up to 90 kV and a maximum voltage of 145 kV has been attained. The cavity has also been used to flattop the integrated energy gain per turn. A description of the cavity design and a summary of the operating experience are given. >