Injector line is really important to generate stable and accurate FEL (Free Electron Laser) and many user need high peak current in the electron beam bunches. Therefore, pulsed beam will be generated at TARLA injector line.
Totally normal conducting technology injector line will consist of a 250 keV (300 keV is design operating voltage) thermionic electron source, two buncher cavities operating 260 MHz and 1.3 GHz, solenoid magnets, steerer magnets, view screens, multislit or pepper pot mask, ICT/FCT (integrated current transformer and fast current transformer), BPM(Beam position monitor), BLM(Beam loss monitor), Laser aliment system, aperture and some vacuum chamber components (like pneumatic valves). At ELBE, operating gun measurement results in macro pulsed mode show that bunch to bunch energy spread arises due to the beam loading at gun. Therefore, there will be a macropulser in order to adjust beam time from CW to macro pulsed mode. The layout of the injector is given in Figure1.
CW (Continuous-wave) electron bunches are generated by a grid just after the cathode and have about 500 ps FWHM length at the exit of the source. This electron bunches then enters the SHB (Subharmonic buncher-260MHz) and gets compressed in a long drift path by the energy modulation produced in the SHB. After that all bunches will compress by the FB (Fundamental buncher 1.3 GHz). Expected electron bunches length will be around 10ps entrance of the first SC (Superconducting) cavity. To prevent back emitted field from first SC cavity, Injector line will bended 10 degree. Electron beam diagnostic equipments will take part like Figure-1 to measure electron charge, size, emittance, position, and losses.
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