Upgrades of beam diagnostics in support of emittance-exchange experiments at the Fermilab A0 photoinjector

The possibility of using electron beam phase space manipulations to support a free-electron laser accelerator design optimization has motivated our research. An on-going program demonstrating the exchange of transverse horizontal and longitudinal emittances at the Fermilab A0 photoinjector has benefited recently from the upgrade of several of the key diagnostics stations. Accurate measurements of these properties upstream and downstream of the exchanger beamline are needed. Improvements in the screen resolution term and reduced impact of the optical system's depth-of-focus by using YAG:Ce single crystals normal to the beam direction will be described. The requirement to measure small energy spreads (<10 keV) in the spectrometer and the exchange process which resulted in bunch lengths less than 500 fs led to other diagnostics performance adjustments and upgrades as well. A longitudinal to transverse exchange example is also reported.Comment: 16 p

HELL: High-energy electrons by laser light, a user-oriented experimental platform at ELI beamlines

Laser wake field acceleration (LWFA) is an efficient method to accelerate electron beams to high energy. This is a benefit in research infrastructures where a multidisciplinary environment can benefit from the different secondary sources enabled, having the opportunity to extend the range of applications that is accessible and to develop new ideas for fundamental studies. The ELI Beamline project is oriented to deliver such beams to the scientific community both for applied and fundamental research. The driver laser is a Ti:Sa diode-pumped system , running at a maximum performance of 10 Hz, 30 J, and 30 fs. The possibilities to setup experiments using different focal lengths parabolas, as well as the possibility to counter-propagate a second laser beam intrinsically synchronized, are considered in the electron acceleration program. Here, we review the laser-driven electron acceleration experimental platform under implementation at ELI Beamlines, the HELL (High-energy Electrons by Laser Light) experimental platform

Two-bunch operation with ns temporal separation at the FERMI FEL facility

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COMMISIONING OF THE FERMI@ELETTRA LASER HEATER*

Abstract The linac of the FERMI seeded free electron laser includes a laser heater to control the longitudinal microbunching instability, which otherwise is expected to degrade the quality of high brightness electron beam sufficiently to reduce the FEL power. The laser heater consists of a short undulator located in a small magnetic chicane through which an external laser pulse enters to modulate the electron beam energy both temporally and spatially. This modulation, which varies on the scale of the laser wavelength, together with the effective R52 transport term of the chicane increases the incoherent energy spread (i.e., e-beam heating). We present the first commissioning results of this system, and its impact both upon the electron beam phase space, and upon the FEL output intensity and quality

Two-Bunch Operation at the FERMI FEL Facility

International audienceFERMI is a linac-driven free electron laser (FEL) based upon the High Gain Harmonic Generation (HGHG) scheme. In standard conditions a bunch of 700 pC of charge with sub mm-mrad emittances is accelerated to 1.2-1.5GeV in a normal conducting S-band linac and drives FEL-1 or FEL-2 undula-tor line, which lase respectively in the range 100-20nm or 20-4nm. A number of two-color schemes have been implemented at FERMI for pump/probe experiments, all consisting in making two portions of the same electron bunch lase at two different wavelengths, with a time-separation from 0 to few hundreds of fs. In order to increase the time separation to ns and tens of ns we have explored the acceleration of two inde-pendent electron bunches separated by multiple of the linac main radio-frequency period, i.e. 333ps. Measure-ments and characterization of this two-bunch mode oper-ation are presented, including trajectory control, impact of longitudinal and transverse wakefields on the trailing bunch and manipulation of the longitudinal phase space