Accelerators and ion storage ring TSR

Stored ion species

Overview of beam intensities

The TSR receives positive ions from a pulsed negative ion sputter source followed by a stripping process in the terminal of the tandem accelerator and optional second and third stripping processes before and after the post accelerator. In order to accumulate heavy ions in the TSR, MULTITURN injection is used. With the application of MULTITURN injection the horizontal machine acceptance can be filled in typically 100 - 200 µs corresponding to a hundred turns allowing an increase in the stored current by a maximum factor of 40 compared to the injector current (using a tandem beam with a typical emittance of 1.5 π mm mrad). A further accumulation method applied at the TSR utilizes the electron cooler. The phase space of the stored beam is compressed by electron cooling thus making phase space available which can be filled by a next MULTITURN injection. This accumulation method is called electron cooling stacking (ECOOL stacking). The achieved intensity with these injection methods is given for some ion species in the following table. The intensities for the singly charged ions HD⁺, Li⁺ and Be⁺ are given by only applying MULTITURN injection.

With optimized electron cooling, currents up to 2 mA can be stored stable, limited by the onset of transverse coherent instabilities. The highest intensity of 18 mA for a ¹²C⁶⁺ beam could only be accumulated by misaligning the electron beam with respect to the ion beam.