Spreading times of ion-bunches in the Cryogenic Trap for Fast ion beams

• Ion-bunch decay measurements in the self-bunching mode of an EIBT.
• Study of the spreading time as a function of the number of ions.
• Observation of an upper spreading-time limit.

The decay of ion-bunches stored in the self-bunching mode of an electrostatic ion beam trap (EIBT) has been investigated as a function of the number of injected ions with the Cryogenic Trap for Fast ion beams (CTF) located at the Max Planck Institute for Nuclear Physics in Heidelberg. By use of the pickup-electrode signal the dependence of the characteristic bunch-spreading time τ, i.e. the time in which the bunch width increases by one third, on the number of injected ions is determined. For F− ions with an initial bunch length of 2.7 μs the spreading times are observed to increase approximately linearly with the number of injected ions and to reach a constant value of ∼10 s for ion numbers larger than 4 × 105.

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