A mid-infrared oscillator FEL has been commissioned at the Fritz Haber Institute. The accelerator consists of a thermionic gridded gun, a subharmonic buncher, and two S-band standing-wave copper structures. It provides a final electron energy adjustable from 15 to 50 MeV, low longitudinal (< 50 keV ps) and transverse emittance (< 20 πmm mrad), at more than 200 pC bunch charge with a micro-pulse repetition rate of 1 GHz and a macro-pulse length of up to 15 <i>µ</i>s. Pulsed radiation with up to 100 mJ macro-pulse energy at about 0.5% FWHM bandwidth is routinely produced in the wavelength range from 4 to 48 <i>µ</i>m. A characterization of the FEL performance in terms of pulse energy, bandwidth, and micro-pulse shape of the IR radiation is given. In addition, selected user results are presented. These include, for instance, spectroscopy of bio-molecules (peptides and small proteins) either conformer selected by ion mobility spectrometry or embedded in superfluid helium nano-droplets at 0.4 K, as well as vibrational spectroscopy of mass-selected metal-oxide clusters and protonated water clusters in the gas phase.
Next generation x-ray sources require very high-brightness electron beams that are typically at or beyond the present state-of-the-art, and thus place stringent and demanding requirements upon the electron injector parameters. No one electron source concept is suitable for all the diverse applications envisaged, which have operating characteristics ranging from high-average-current, quasi-CW, to high-peak-current, single-pulse electron beams. Advanced Energy Systems, in collaboration with various partners, is developing several electron injector concepts for these x-ray source applications. The performance and design characteristics of five specific RF injectors, spanning "L" to "X"-band, normal-conducting to superconducting, and low repetition rate to CW, which are presently in various stages of design, construction or testing, is described. We also discuss the status and schedule of each with respect to testing.
The IR free-electron laser (IR FEL) at Jefferson Laboratory has achieved steady-state 3 micron lasing at a power level of 1.7 kW. Efforts to upgrade this device to 10 kW operation over the next three year are underway. As a result of this success and recent technology advances, free-electron lasers (FEL) should be considered a serious option for high-power, commercial material processing and military applications. The discriminating attributes of FELs are their wide-band tunability, their implicit potential for very high-power operation due to the vacuum lasing medium, and the intrinsic picosecond pulse structure that promises superior performance in certain material processing applications. Applications spanning high-value-added micromachining to low-value-added, high-power, high-throughput surface processing of metals and polymers are identified. The projected economics and market insertion point for a potential commercial application in polymer processing is described. Concepts for compact high-power FEL systems based upon superconducting RF accelerometers with energy recovery are defined. Key technology issues on the path to commercial deployment, such as the demonstration of reliable, high- current photo-cathode injectors, are identified and discussed. It is concluded that the first commercial material processing FEL beta units could be coming on line in about five years.
An efficient MW-class free electron laser (FEL) directed energy weapon (DEW) system holds promise for satisfying shipboard self-defense (SSD) requirements on future generations of Navy vessels because of the potential for high- power operation and the accessibility to all IR wavelengths. In order to meet shipboard packaging and prime power constraints, the power efficiency and high real-estate gradient achievable in a FEL driven by a superconducting rf accelerator is attractive. Configuration options and the key development issues for such a system are described.
The Compact Infrared Free Electron Laser (CIRFEL) was built as part of a joint collaboration between Northrop Grumman and Princeton University to develop FEL's for use by researchers in the materials, medical and physical sciences. The CIRFEL was designed to laser in the Mid-IR and Far-IR regimes with picosecond pulses, megawatt level peak powers and an average power of a few watts. The CIRFEL utilizes an RF photocathode gun to produce high-brightness time synchronized electron bunches. The micropulse separation is 7 nsec which allows a number of relaxation phenomena to be observed. In addition, the photocathode illumination laser can be used in combination with the FEL IR light for pump- probe experiments. The CIRFEL is presently being commissioned and working towards lasing. The present status of the machine is presented.
Conference Committee Involvement (1)
Advances in X-ray Free-Electron Lasers Instrumentation