needle cathode emitter; electron bunch diagnostics; UV pulse synthesizer; XFEL; photo emission; field emission; low-emittance electron source; laser pulse shaping; UV femtosecond laser; cold electron source
Patterson Bruce (2011), Can energetic THz pulses initiate surface catalytic reactions on the picosecond time scale?, in CHIMIA
, 65, 323-325.
Trisorio Alexandre, Ruchert Clemens, Hauri Christoph (2011), Direct shaping of picosecond high energy deep ultraviolet pulses, in Applied Physics B
, 105, 255-261.
Hauri Christoph, Ruchert Clemens, Vicario Carlo, Ardana Fernando (2011), Strong field single-cycle THz pulses generated in an organic crystal, in Applied Physics Letters
, 99, 161116-161118.
Ruchert Clemens, Ardana Fernando, Trisorio Alexandre, Vicario Carlo, Hauri Christoph (2011), Towards high-power single-cycle THz laser for initiating high-field-sensitive phenomena, in CHIMIA
Trisorio Alexandre, Paul Pierre-Marie, Ple Fabien, Ruchert Clemens, Vicario Carlo, Hauri Christoph (2011), Ultrabroadband TW-class Ti:sapphire laser system with adjustable central wavelength, bandwidth and multi-color operation, in Optics Express
, 19(21), 20128-20140.
Hauri Christoph (2010), Intrinsic emittance reduction of an electron beam from metal photocathode, in Physical Review Letters
, 104, 234802-234805.
Ruchert Clemens, Scaling submillimeter single-cycle transients toward megavolts per centimeter field strength via optical rectification in the organic crystal OH1, in Optics Letters
, 37, 899-901.
Understanding the physical process of ultrashort electron bunch formation, the ability for controlling their physical properties (charge, energy spread, longitudinal/transverse shape, emittance) and finally their accurate characterization has become more and more important for many different applications such as, for example, electron holography, femtosecond electron diffraction and electron microscopy. In addition, future accelerator projects such as x-ray free electron laser sources (X-FELs) would tremendously profit from such well-controlled and well-characterized electron bunches with a low emittance at a high brightness. The most established electron gun today providing pulsed electron bunches at high-brightness and low emittance is the laser-assisted photo-gun, where UV laser pulses synchronized to a radio frequency (RF) electromagnetic wave are used to deliberate electrons subsequently accelerated in the RF field. In such laser-driven guns the time structure, emittance and space-charge effects of the emitted electron bunch depends to a large extent on the UV laser pulse. The ideal laser pulse would deliver well-defined intense, ultrashort pulses in the UV with arbitrarily choosable properties in time, space and frequency. Thus such stringent requirements on UV pulses need fundamental new concepts in UV laser beam shaping and amplifier technology. In this proposal we want (1) to systematically investigate and optimize the process of laser-assisted (field-) emission of different electron sources ranging form conventional (flat cathodes) to novel emitters (needle cathodes, field emitter arrays) by help of a novel tunable laser system, and (2) to develop a novel time-resolved non-relativistic electron bunch diagnostic tool based on laser ponderomotive scattering to investigate fundamental aspects (such as time-resolved Fermi-dirac distribution mapping) and explore conditions for best laser-electron pulse mapping in the immediate vicinity of the electron gun. This novel diagnostic tool should allow slice-emittance monitoring at nonrelativistic electron energies for the first time. Presently slice-emittance measurements are usually performed several tens of meters downstream the electron source in the relativistic regime and might not reflect the initial source emittance. The essential tool for such control and diagnose electron bunches is an intense and ultrastable laser source delivering ultrashort pulses with adjustable photon energy, controllable intensity and pulse duration, arbitrarily adaptable temporal and transverse beam profile both in the UV and mid-IR. The requirements for such a laser system go beyond what state-of-the-art laser system can provide and need novel approaches. PSI has currently started to develop such a unique laser system in collaboration with an industrial partner and the system is expected to be available for fundamental research mid 2008. The work proposed here will highly profit from the support of PSI groups such as beam diagnostics group, beam dynamics group as well as the support of workshop and mechanical engineering department. The close connection to the PSI-XFEL project and to University of Berne assures disposability of a great part of the equipment and a stimulating academic atmosphere both being important prerequisites for a successful PhD project.