Because uniformly filled ellipsoidal 'waterbag' bunches have linear self-fields in all dimensions, they do not suffer from space-charge induced brightness degradation. This in turn allows very efficient longitudinal compression of high-brightness bunches at sub or mildly relativistic energies, a parameter regime inaccessible up to now due to detrimental effects of non-linear space-charge forces. To demonstrate the feasibility of this approach, we investigate ballistic bunching of 1 MeV, 100 pC waterbag electron bunches, created in a half-cell rf-photogun, by means of a two-cell booster-compressor. Detailed GPT simulations of this table-top set-up are presented, including realistic fields, 3D space-charge effects, path-length differences and image charges at the cathode. It is shown that with a single 10 MW S-band klystron and fields of 100 MV/m, 2 kA peak current is attainable with a pulse duration of only 30 fs at a transverse normalized emittance of 1.5 µm.
|Number of pages||6|
|Journal||International Journal of Modern Physics A: Particles and Fields, Gravitation, Cosmology, Nuclear Physics|
|Publication status||Published - 2007|