UVSOR, Okazaki
Coherent synchrotron radiation (CSR) has been intensively investigated because of its potential ultrahigh power in the terahertz (THz) region. CSR is emitted not only from short electron bunches but also from bunches with longitudinal microstructure of radiation wavelength scale. Laser slicing is a technique for creating sub-mm dip structure on electron bunches circulating in a storage ring. Such a bunch emits broadband CSR of sub-ps duration. More generally, in principle, one can produce arbitrary density structures by the laser electron interaction. As a useful example, periodic density structures can be produced by using amplitude-modulated laser pulses. The period of the structure can be varied by changing the period of the amplitude modulation. The first successful demonstration was conducted at UVSOR-II. The electron bunch with the periodic density modulation emitted monochromatic and tunable THz-CSR in a bending magnet. In this talk, some latest results from the THz CSR experiments with laser modulation technique at UVSOR-II will be presented, including the direct measurement of the CSR electric field and beam dynamics of the micro-density structures on electron bunches.
Some results are from joint researches by UVSOR, PhLAM, Nagoya U., Kyoto U. and Osaka U
DESY, Hamburg
PSI, Villigen
Electro Optical (EO) sampling is a promising non-destructive method for measuring ultra short (sub-ps) electron bunches. The FEMTO slicing experiment at the Swiss Light Source modulates about 3 pC of the 5 nC electron bunch longitudinally. The coherent synchrotron radiation (CSR) emitted by this substructure was measured in a single shot EO technique in gallium phosphide (GaP) using pulses from an Yb fiber laser. The arrival time jitter and the broadening of this ps long structure over several turns of the synchrotron could be measured with sub-ps resolution.