Characteristics and Properties of the Jefferson Lab ERL and Applications of the High Brightness 4th Generation Light Source for High Pressure Research
Gwyn P. Williams & the JLab Team
Jefferson Laboratory
Jefferson Lab operates a fourth generation accelerator-based light source. The facility is based on an Energy Recovered Linac (ERL)1, which has a significant advantage in brightness over a conventional electron storage ring (synchrotron) source. Both terms contributing to the brightness are enhanced. The power is enhanced by multiparticle coherent effects2, while the source size is smaller because the horizontal emittance is approximately equal to the vertical emittance (round beams). This type of source has additional advantages in that the bunch lengths are in the 100's of femtosecond range, allowing ultrafast phenomena to be studied in the time domain. The JLab facility incorporates 3 sources: (1). A 10 kW av. power 1-14 micron tunable Infrared Free Electron Laser (IRFEL) with energies of 120 microJoules per pulse (close to 1030 photons/sec): (2). A 1 kW av. power 250 nm to 1 micron UVFEL with up to 25 microJoules per pulse: and (3). A 0.1 to 5 THz source3 with 1 microJoule per pulse. All 3 sources can operate at pulse repetition frequencies up to 75 MHz and pulse lengths in the range 250 - 2000 femtoseconds.
We will present details of the source, and will make comparisons with storage ring sources and x-ray FELs. We will then discuss applications of this type of source for high pressure research in the far-IR, one example being the opportunity to measure the Drude absorption at long wavelengths, which signals the onset of conductivity. Here, some of the key issues have to do not just with brightness, but with noise. There is also the possibility to drive out-of-equilibrium phenomena with multiple photon beams. Finally we will briefly mention the characteristics of Jefferson Lab’s a 6GeV accelerator, which is capable of producing sub-picosecond x-rays with a brightness comparable to dipole radiation at a storage ring.
References:
1.
G.R. Neil et al, Phys. Rev. Let. 84, 662 (2000)2. C. J. Hirschmugl, M. Sagurton and G. P. Williams, Physical Review A44, 1316, (1991)
3. G.L. Carr, et al, Nature 420 153 (2002)
This work supported by the Office of Naval Research, the Joint Technology Office, the Commonwealth of Virginia, the Air Force Research Laboratory, The US Army Night Vision Lab, and by DOE under contract DE-AC05-84ER40150.
