The JLab high power ERL light source

Abstract

A new THz/IR/UV photon source at Jefferson Lab is the first of a new generation of light sources based on an Energy-Recovered, (superconducting) Linac (ERL). The machine has a 160 MeV electron beam and an average current of 10 mA in 75 MHz repetition rate hundred femtosecond bunches.These electron bunches pass through a magnetic chicane and therefore emit synchrotron radiation. For wavelengths longer than the electron bunch the electrons radiate coherently a broadband THz $ half cycle pulse whose average brightness is 45 orders of magnitude higher than synchrotron IR sources. Previous measurements showed 20 W of average power extracted [Carr, et al., Nature 420 (2002) 153]. The new facility offers simultaneous synchrotron light from the visible through the FIR along with broadband THz production of 100 fs pulses with 4200 W of average power.The FELs also provide record-breaking laser power [Neil, et al., Phys. Rev. Lett. 84 (2000) 662]: up to 10 kW of average power in the IR from 1 to 14 mm in 400 fs pulses at up to 74.85 MHz repetition rates and soon will produce similar pulses of 300-1000 nm light at up to 3 kW of average power from the UV FEL. These ultrashort pulses are ideal for maximizing the interaction with material surfaces. The optical beams are Gaussian with nearly perfect beam quality. See www.jlab.org/FEL for details of the operating characteristics; a wide variety of pulse train configurations are feasible from 10 ms long at high repetition rates to continuous operation.The THz and IR system has been commissioned. The UV system is to follow in 2005. The light is transported to user laboratories for basic and applied research. Additional lasers synchronized to the FEL are also available. Past activities have included production of carbon nanotubes, studies of vibrational relaxation of interstitial hydrogen in silicon, pulsed laser deposition and ablation, nitriding of metals, and energy flow in proteins. This paper will present the status of the system and discuss some of the discoveries we have made concerning the physics performance, design optimization, and operational limitations of such a first generation high power ERL light source. r

Experimental investigation of an optimum configuration for a high-voltage photoemission gun for operation at≥500 kV

“…A dc photoemission gun with a GaAs or alkali photocathode is one of the most promising candidates for such guns, because a high-current beam of 9 mA has been routinely provided by the dc gun at the Jefferson Lab FEL [2], and a record high current of 65 mA was recently demonstrated at the Cornell photoinjector [3]. Generation of high brightness beam with 90% normalized emittances of 0.29 μm in the vertical plane and 0.51 μm in the horizontal plane with bunch charge of 77 pC was also demonstrated at the Cornell photoinjector with a 350 kV photoemission gun equipped with a GaAs photocathode [4].…”

Terahertz radiation sources based on free electron lasers and their applications

“…The output power of these high power oscillator FELs is limited by mirror heating, leading to surface distortion [31,32]. The Novosibirsk group has proposed a novel outcoupling scheme, called the electron output scheme, for high power FEL applications [31].…”

Strategies towards a compact XUV free electron laser adopted for the LUNEX5 project

“…Then, UV-VUV FEL oscillators [23][24][25][26][27][28][29][30] were actively developed and studied, with short wavelength achievements [31,32]. In the path towards the control of FEL properties, linewidth narrowing has been performed with a Fabry-Perot etalon [33] and possible handling of the temporal structure was carried out [34][35][36][37][38][39].…”