Vladimir N. Litvinenko

Lasing in visible and ultraviolet regions in an optical klystron installed on the VEPP-3 storage ring

Abstract Lasing in a wide 2400–6900 A spectral range (from visible to ultraviolet) was reached in the optical klystron OK-4 installed on the VEPP-3 storage ring. OK-4 is the first FEL operating in UV.

A free electron laser-photoemission electron microscope system (FEL-PEEM)

We report first results from our effort to couple a high resolution photoemission electron microscope (PEEM) to the OK-4 ultraviolet free electron laser at Duke University (OK-4/Duke UV FEL). The OK-4/Duke UV FEL is a high intensity source of tunable monochromatic photons in the 3–10 eV energy range. This tunability is unique and allows us to operate near the photoemission threshold of any samples and thus maximize sample contrast while keeping chromatic berrations in the PEEM minimal. We have recorded first images from a variety of samples using spontaneous radiation from the OK-4/ Duke UV FEL in the photon energy range of 4.0–6.5 eV. Due to different photothreshold emission from different sample areas, emission from these areas could be turned on (or off) selectively. We have also observed relative intensity reversal with changes in photon energy which are interpreted as density-of-state contrast. Usable image quality has been achieved, even though the output power of the FEL in spontaneous emission mode was several orders of magnitude lower than the anticipated full laser power. The PEEM has achieved a spatial resolution of 12 nm.

The VEPP-3 storage-ring optical klystron: Lasing in the visible and ultraviolet regions

Abstract Lasing in a wide spectral range (from visible to ultraviolet, 2400–6900 A) was reached in the optical klystron OK-4 installed on the VEPP-3 storage ring. OK-4 is the first FEL operating in UV.

Status of the INP optical klystron

Abstract The result of recent experiments with the optical klystron OK-2 installed in the storage ring VEPP-3 are presented. The current status, the new magnetic system design OK-3, and some prospects and plans are described.

Giant laser pulses in the Duke storage ring UV FEL

Abstract We have studied the dynamics of giant pulse generation in the Duke UV FEL with peak power of several gigawatts. The giant pulses will be provided by a FEL gain modulation technique developed for the OK-4 UV FEL at Novosibirsk, Russia. A new mechanism for “super-pulse” generation was discovered during these studies. It allows the generation of peak power up to 10 GW using the “phase space” refreshment of the electron beam caused by synchrotron motion [V. Litvinenko et al., to be published]. We have developed a new macro-particle code for giant pulse simulation including all known mechanisms of storage ring FEL interaction. Results of these giant pulse simulations are presented in the paper.

Duke storage ring UV/VUV FEL: status and prospects

Abstract A 1.1 GeV electron storage ring dedicated for UV-VUV FEL operation was commissioned last year at the Duke University Free Electron Laser Laboratory [V.N. Litvinenko et al., Commissioning of the Duke storage ring, Proc. 1995 Particle Accelerator Conf., Dallas, TX, May 1–5, 1995]. The XUV FEL project, based on the collaboration of the Duke FEL Laboratory and Budker Institute for Nuclear Physics (Novosibirsk, Russia) is described. The OK-4 UV FEL has arrived from Novosibirsk at the Duke FEL laboratory and is in the process of installation. The main parameters of the Duke Free Electron Laser Laboratory (DFELL) storage ring, the OK-4 optical klystron, and the experimental set-up are presented. The parameters of the UV-VUV FEL are given and possible future upgrades to this system are discussed. We have developed a new macro-particle code for storage ring simulation including all known mechanisms of storage ring FEL interaction. We confirm our expectations on the average and peak power for the OK-4. In addition we have studied a giant pulse mode of operation. A new mechanism of “super-pulse” generation was discovered during these studies. It allows the generation of peak power up to 10 GW using “phase-space” refreshment of the electron beam caused by synchrotron motion [V.N. Litvinenko, B. Burnham, J.M.J. Madey and Y. Wu, Nucl. Instr. and Meth. A 358 (1995) 334].

High-power inverse Compton γ-ray source at the Duke storage ring

A 1.1 GeV electron storage ring dedicated for UV-VUV FEL operation was commissioned last year at the Duke University Free Electron Laser Laboratory (DFELL). The UV-VUV OK-4 FEL project, based on the collaboration of the Duke FEL Laboratory and Budker Institute for Nuclear Physics (BINP, Novosibirsk, Russia) is under way. The OK-4 FEL has arrived at the Duke FEL Laboratory from Novosibirsk and is in the process of installation. High average intracavity power and natural synchronization of electron and optical pulses in the OK-4 FEL allow the production of intense inverse Compton (gamma) -rays (5-150 MeV) on the return pass of the optical pulse. The projected intensity of this (gamma) -ray source allows high energy resolution with simple geometric collimation of the (gamma) -rays. The wide tunability of the OK-4 FEL also allows us to control the (gamma) -ray energy. In this paper we discuss the processes involved in (gamma) -ray production, the influence of beam parameters and geometry on (gamma) -ray energy spread, and present projected performance of the Duke/OK-4 inverse Compton (gamma) -ray source for two simple cases. The studies reported in this paper were performed in 1993. Results were presented at the 1994 Free Electron Laser Conference (22-26 August 1994, Stanford, CA) but were published only as internal DFELL reports. A group of scientists from the Triangle University Nuclear Laboratory (TUNL) also ran independent simulations in 1994 which confirm our predictions. A workshop on the DFELL-TUNL (gamma) -ray facility was held in Durham from December 16-17, 1994 to discuss unique features of this facility and its utilization for nuclear physics and pion spectroscopy.

Commissioning of the Duke Storage Ring

The commissioning of the 1 GeV Duke Storage Ring began in November, 1994 with the demonstration of injection, storage and ramping to 1 GeV at the first attempt. The ring is now operational. The Duke project is unique in that the storage ring and linac were designed, constructed and commissioned by a small new University laboratory, operating on a low budget. The team is comprised of six accelerator physicists and graduate students, eight engineers, and fifteen technicians.

Dynamic aperture study for the Duke FEL storage ring

Abstract The new lattice design of the Duke free electron laser (FEL) storage ring is described. The results of the 6-dimensional dynamic aperture study using single particle tracking codes are presented. The influence of 8-m FEL undulator on the dynamic aperture is studied.

High Current Energy Recovery Linac at BNL

We present the design and parameters of an energy recovery linac (ERL) facility, which is under construction in the Collider-Accelerator Department at BNL. This R&D facility has the goal of demonstrating CW operation of an ERL with an average beam current in the range of 0.1 - 1 ampere and with very high efficiency of energy recovery. The possibility of a future upgrade to a two-pass ERL is also being considered. The heart of the facility is a 5-cell 703.75 MHz super-conducting RF linac with strong Higher Order Mode (HOM) damping. The flexible lattice of the ERL provides a test-bed for exploring issues of transverse and longitudinal instabilities and diagnostics of intense CW electron beams. This ERL is also perfectly suited for a far-IR FEL. We present the status and plans for construction and commissioning of this facility.