Systematic Studies of the Micro-Bunching Instability at Very Low Bunch Charges

TL;DR

This paper investigates the micro-bunching instability at very low bunch charges in a synchrotron, analyzing bursting behavior in different current regimes and validating results with numerical modeling.

Contribution

It provides the first detailed measurements of bursting behavior in two distinct current regimes at very low bunch charges, supported by numerical solutions.

Findings

Bursting occurs in two separate current regimes with a stable region in between.

Measurements align well with Vlasov-Fokker-Planck simulations.

The study enhances understanding of micro-bunching instability dynamics.

Abstract

At KARA, the KArlsruhe Research Accelerator of the KIT synchrotron, the so called short bunch operation mode allows the reduction of the bunch length down to a few picoseconds. The micro- bunching instability resulting from the high degree of longitudinal compression leads to fluctuations in the emitted THz radiation, referred to as bursting. For extremely compressed bunches at KARA, bursting occurs not only in one but in two different bunch-current ranges that are separated by a stable region. This work presents measurements of the bursting behavior in both regimes. Good agreement is found between data and numerical solutions of the Vlasov-Fokker-Planck equation.