The First Year of Operation at the Heidelberg Heavy-Ion Postaccelerator

The 3MV stage of the Heidelberg Heavy Ion Postaccelerator being the first one to use the independent phasing concept of short linear accelerator cavities in a booster application behind an MP-Tandem accelerator, went into operation in December 1977 and is in the state of full user-availability since May of 1978. The machine uses spiral resonators at room temperature. Ten such resonators with design velocity ß
₀
= 0.10 at 108.48 MHz are operated either in CW at 20 kW or in pulsed mode (df = 0.25) at 80 kW. Due to the flexibility of the independent phasing of the 10 resonators presently in operation, acceleration voltages as high as 3.3 MV (CW) could be demonstrated for ions between
¹²
C and
⁵⁸
Ni. 5.5 MV have been achieved in pulsed operation. An energy resolution of ΔE/E2 4 . 10
^-4
allowing rebunched pulse widths of
^Δt
FWHM < 70 ps could be measured, showing the tandem like beam quality. The machine is exclusively computer controlled, prerequisite for the operation of the many parameters of a tandem-postaccelerator-combination. The overall availability of the postaccelerator together with the MP Tandem was above 80% of the scheduled user beam time. The operation of the 3 MV stage will be interrupted for a 4 months' shutdown late 1979 to allow for the extension of the machine to its full 10 MV (CW) acceleration voltage by the addition of 20 more spiral resonators.