Litvinenko, V.
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| MOOA002 | Optics-Free FEL Oscillator | |
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Funding: Work performed under the auspices of the U.S. Department of Energy Optics-free FEL oscillators will combine two of most attractive FEL features, wavelength tunability and high power capability, with high laser beam quality and its spectral purity. High losses make optical feedback impractical in many interesting ranges of spectrum. The concept of "electron out-coupling", invented in 1985 by Nikolay Vinokurov, became the basis of a feed-back schemes using bunched electron beam. The e-beam feedback does not suffer from optics shortcomings, such wavelength and power limitations, but instead requires a high quality electron beams. In this paper will focus on an optics-free oscillator using a single FEL system with one or two electron beams. We will discuss the limitation of this scheme and present two examples of its possible realization in FIR and X-ray ranges of spectrum. |
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| MOPP026 | Simulations, Diagnostics and Recent Results of the VISA II Experiment | 83 |
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The VISA II experiment entails use of a chirped beam to drive a high gain SASE FEL. The output radiation is diagnosed with a modified frequency resolved optical gating (FROG) technique. Sextupoles are implemented to correct the lonigtudinal aberrations affecting the high energy spread chirped beam during transport to the undulator. The double differential energy spectrum is measured with a pair of slits and a set of gratings. In this paper, we report on start-to-end simulations, radiation diagnostics, as well as intial experimental results; experimental methods are described. |
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| TUOA002 | High Average Power Optical FEL Amplifiers | 232 |
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Historically, the first demonstration of the FEL was in an amplifier configuration at Stanford University. There were other notable instances of amplifying a seed laser, such as the LLNL amplifier and the BNL ATF High-Gain Harmonic Generation FEL. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance a 100 kW average power FEL. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting energy recovery linacs combine well with the high-gain FEL amplifier to produce unprecedented average power FELs with some advantages. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department. |
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| MOPP054 | Electron Gun and Injector Designs for State-of-the-Art FELs | |
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Funding: This work is supported by the Naval Sea Systems Command, the Office of Naval Research, the DoD Joint Technology Office, the Missile Defense Agency and the US Department of Energy. Reliable, high-brightness, high-power injector operation is a critical technology issue for energy recovery linac drivers of high-power free electron lasers (FEL). Advanced Energy Systems is involved in three ongoing injector programs that target up to 0.5 Ampere current levels at emittance values consistent with the requirements of the FEL. One is a DC photocathode gun and superconducting RF (SRF) booster cryomodule. A 748.5 MHz injector of this type is being assembled and will be tested up to 100 mA at the Thomas Jefferson National Accelerator Facility (JLAB) beginning in 2007. The second approach being explored is a high-current normal-conducting RF photoinjector. A 700 MHz gun, presently under fabrication, will undergo thermal test in 2006 at Los Alamos National Laboratory (LANL). Finally, a half-cell 703.75 MHz SRF gun is presently being designed and will be tested to 0.5 Ampere at Brookhaven National Laboratory (BNL) in 2007. The status and projected performance for each of these injector projects is presented. |
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| WEOA004 | Phase-Space Tomography of Giant Pulses in Storage Ring FEL: Theory and Experiment | |
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The use of giant pulses in storage ring FEL provides for high peak power at the fundamental wavelength and for effective generating of high VUV harmonics. This process is accompanied by a complex nonlinear dynamics of electron beam, which cannot be described by simple models. In this paper we compare the results of numerical simulations, performed by self-consistent #uvfel code, with experimental observations of electron beam evolution in the longitudinal phase space. The evolution of the electron beam distribution was obtained from the images recorded by dual-sweep streak-camera. The giant pulse process occurs on a short fast time scale compared with synchrotron oscillation period, which make standard methods of tomography inapplicable. We had developed a novel method of reconstruction, an SVD-Based Phase-Space Tomography, which allows to reconstruct phase space distribution from as few as two e-bunch profiles separated by about 3 degrees of rotation in the phase space. This technique played critical role in reconstructing the evolution of electron beam evolution during giant pulse. |
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| THPP063 | Transverse Laser Beam Shaping in High Brightness Electron Gun at ATF | |
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The brightness of electron beams from a photo injector is influenced by the transverse and longitudinal distribution of the laser beam illuminating the cathode. Previous studies at Brookhaven Accelerator Test Facility have shown that formation of an ideal e-beam with lowest transverse emittance requires uniform circular distribution of the emitted electrons. The use of the uniformly distributed power of the laser beam may not lead to that of the emitted electrons because of the non-uniform quantum efficiency. A proper shaping of the laser beam can compensate for this non-uniformity. In this paper we describe the use of digital light processing (DLP) technique based on digital mirror device (DMD) for spatial modulation of the laser beam, for measurements of the quantum efficiency map, and for creating the desirable e-beam density profiles. A DMD is aμelectronic mechanical system (MEMS) comprising of millions of highly reflectiveμmirrors controlled by underlying electronics. We present experimental results of the influence of the various spatial profiles on the e-beam emittance. |
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| THPP071 | A Method of Emittance Preservation in ERL Merging System | 644 |
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Funding: Work performed under the auspices of the U.S. Department of Energy Energy recovery linacs (ERLs) are potential candidates for the high power and high brightness electron beams sources. The main advantages of ERL are that electron beam is generated at relatively low energy, injected and accelerated to the operational energy in a linac, and after the use is decelerated in the same linac down to injection energy, and, finally, dumped. A merging system, i.e. a system merging together high energy and low energy beams, is an intrinsic part of any ERL loop. One of the challenges for generating high charge, high brightness electron beams in an ERL is development of a merging system, which provides achromatic condition for space charge dominated beam and which is compatible with the emittance compensation scheme. In this paper we present the theory, the principles of operation and some designs (including simulations) of such merging systems. We use a specific implementation for R&D ERL at Brookhaven as the illustration. |
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