Longitudinal density modulation of unstable bunches emitting coherent IR

B. Podobedov, G.L. Carr, S.L. Kramer, J.B. Murphy
PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268)  
Observations of coherent infrared (IR) light emissions from 30 cm long electron bunches at the NSLS VUV ring were reported in [1]. The emissions occurred above some current threshold and had a maximum spectral content near 42 GHz, leading to speculations that they were due to a longitudinal instability creating a 7 mm modulation of the bunch density. To check this experimentally we performed streak camera measurements recording a large number of beam profiles taken both during and between the
more » ... herent emission bursts. In the course of our studies we have directly proven that the longitudinal beam density indeed experiences a significant modulation when coherent emission bursts occur.
doi:10.1109/pac.2001.987228 fatcat:sohgiyi6lzce7p6neuzcgsmvhq