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The development of a hybrid undulator with a small period-to-gap ratio (0.75) for the Novosibirsk Free Electron Laser (FEL) is described. The design of the undulator allows reconstruction of its period and a change in the number of poles. Since the configuration with permanent magnets can be scaled while preserving the field distribution, this design can be used both in installations operating in the terahertz range and for X-ray lasers. The results are presented from computer simulations and calculating the main parameters of the undulator.

The Novosibirsk FEL facility has three FELs installed on the first, second, and fourth orbits of the multiturn energy recovery linac (ERL). The first FEL covers the 90–240 μm range of wavelengths at an average radiation power of 0.5 kW with a pulse repetition rate of 5.6 or 11.2 MHz and a peak power of 1 MW. The second FEL operates in the 40–80 μm range of wavelengths at an average radiation power of 0.5 kW with a pulse-repetition rate of 7.5 MHz and a peak power of around 1 MW. These two FELs are the world’s most powerful (in terms of average power) sources of coherent narrow-band (less than 1%) radiation in their wavelength ranges. The third FEL was commissioned in 2015 to cover the 5–20 μm range of wavelengths. The Novosibirsk ERL is the world’s first and only multiturn ERL. Its distinctive features include a normally-conductive 180 MHz accelerating system, a direct current (DC) electrostatic electron gun with a control grid and thermionic cathode, three operating modes of the magnetic system, and a compact (6 × 40 m) design. The Novosibirsk FEL facility has been in operation for users of terahertz radiation since 2004.

A scheme of electron radiation output is proposed to solve the problem of overheating of the optical resonator mirrors in free-electron lasers (FEL) with high average radiation power. Such a structure acts on the electron beam, which is initially grouped in the first section of the undulator due to interaction with the mode of the optical resonator. In subsequent sections, it rotates at a small angle relative to the optical axis while maintaining its grouping, and its coherent radiation goes beyond the limits of the resonator mode. The electron outcoupling system is installed on the last of the three lasers of the Novosibirsk FEL. It consists of three undulators, two quadrupoles, and dipole correctors located between them. There are thus two possible configurations, as the electron beam can be rotated in both the second and third undulator. Preliminary estimates of the radiation power are considered. Different configurations of the electron radiation output system of the Novosibirsk FEL are compared.

The development of the permanent-magnet variable-period undulator (VPU) is aimed at improving the parameters of the Novosibirsk free electron laser (FEL). The key features of this design are the possibility of increasing the number of poles for shorter periods with constant undulator length and wider radiation wavelength tuning range as compared with conventional undulators. As the idea of the permanent-magnet VPU has not been properly tested yet, there are several issues to be solved before THE manufacture of the device. Two short prototypes of the VPU were made for the purpose of testing solutions to existing problems. We present here the results of mechanical and magnetic measurements of the undulator prototypes and compare the characteristics of the prototypes with those predicted by simulations.

A new normal-conducting, CW, thermocathode RF gun has been developed and tested recently at Budker Institute of Nuclear Physics. Providing an average current of up to 100 mA, this device will be used to upgrade the injector of the Novosibirsk FEL facility. Simulation of beam dynamics in the RF gun and its beamline was performed, the space-charge forces taken into account. Comparison of the simulation results and experimental measurements is presented in this paper.

A new variable period undulator of unique design was developed and built recently at Budker INP. It will replace the electromagnetic undulator in use now on the second FEL of the Novosibirsk FEL facility. As a result, the FEL tunability range will be substantially extended. In this paper, we present the results of measurements of the undulator magnetic field for different periods and discuss ways to reduce the field errors, which include sorting of magnets, weakening of undulator edge poles, and using of steering coils.

Free electron lasers (FELs) are unique sources of electromagnetic radiation with tunable wavelength. A high-power FEL has been created at the G. I.Budker Institute for Nuclear Physics. Its radiation frequency can be tuned over a wide range in the terahertz and infrared spectral ranges. As the source of electron bunches, this FEL uses a multi-turn energy-recovery linac, which has five straight sections. Three sections are used for three FELs which operate in different wavelength ranges (90–240 μm for the first, 37–80 μm for the second, and 5–20 μm for the third ones). The first and the second FELs were commissioned in 2003 and 2009, respectively. They are used for various applied and research problems now. The third FEL is installed on the last, forth accelerator loop, in which the electron energy is the maximum. It comprises three undulator sections and a 40 m optical cavity. The first lasing of this FEL was obtained in the summer of 2015. The radiation wavelength was 9 μm and the average power was about 100 W. The design power is 1 kW at a pulse repetition rate of 3.75 MHz. Radiation of the third FEL will be delivered to user stations from the protected hall in the near future. The third FEL commissioning results are presented and the current status of the first and second FELs as well as their future development prospects are described.

Novosibirsk FEL facility is based on the first in the world multi-turn energy recovery linac (ERL). It comprises three FELs (stages). FELs on the first and the second tracks were commissioned in 2004 and 2009 respectively and operate for users now. The third stage FEL is installed on the fourth track of the ERL. It includes three undulator sections and 40-meters-long optical cavity. The design tuning range of this FEL is from 5 to 20 microns and the design average power at bunch repetition rate 3.74 MHz is about 1 kW. Recent results of the third stage FEL commissioning are reported.

According to leading producers of microelectronic devices, lithography based on free electron lasers (FEL) could become the main technology for the mass production of elements with a scale up to 5 nm in the near future. One of the main hindrances in this path is the absence of working FEL with the required parameters. A feasibility study devoted to the production of such an FEL based on a superconducting energyrecovery linac (ERL) has been carried out at the Budker Institute of Nuclear Physics (BINP). The ERL average current is limited by longitudinal and transverse instabilities, caused by the interaction of an electron beam with the fields induced by it in the superconducting cavities. The estimations of the threshold currents and parameters of the ERL required for the operation of FEL are obtained.

To improve the parameters of the second stage Novosibirsk free electron laser we plan to replace the existing electromagnetic undulator by permanent-magnet variable-period undulator (VPU). The VPUs have several advantages compared to conventional undulators, which include wider radiation wavelength tuning range and an option to increase the number of poles. Both these advantages will be realized in the new undulator under development in Budker INP. There are some technical problems, which have to be solved before this idea can be implemented in practice. To check the solution of these problems we designed and manufactured a small undulator prototype, which has just several periods. In this paper, the results of mechanical and magnetic measurements of this undulator prototype are presented and compared with simulations.

The high-power free electron laser (FEL) facility NovoFEL has been created at Budker INP. Its wavelength can be tuned over a wide range in terahertz and infrared spectrum regions. This FEL uses a multi-turn energy recovery linac with five straight sections as a source of electron beam. Three sections are used for three FELs which operate in different wavelength ranges (the first at 90-240 μm; the second at 37 – 80 μm; the third at 5 – 20 μm). The first and second FELs were commissioned in 2003 and 2009, respectively. They operate for users now. The third FEL is installed on the fourth accelerator track, which is the last one; the electron energy is maximal here. This FEL comprises three undulator sections and a 40-m optical cavity. The first lasing of this FEL was obtained in the summer of 2015. The radiation wavelength was 9 μm and the average power was about 100 W. Radiation of the third FEL was delivered to the user stations, and the first user shifts were performed recently. The results of the commissioning of the third FEL, the current status of the first and second FELs and future development prospects are presented.

According to microelectronic production leaders the lithography based on the free electron laser (FEL) could become the main technology for the elements mass production with scale to 5 nm in the nearest future. One of the main problem is the absence of the working FEL with required parameters. The feasibility study of those FEL based on superconducting energy-recovery linac (ERL) was made in Budker INP. The ERL average current is limited by longitudinal and transverse instabilities, caused by interaction between electron beam and its induced fields in the superconducting cavities. The estimations of the threshold currents and ERL parameters were made.

The design of the large-aperture variable-period undulator (VPU) developed for the Novosibirsk free electron laser (FEL) is shortly described. High amplitude of on-axis field is achieved due to the arc shape of the magnet blocks and poles of the undulator. To conduct magnetic measurements and fine tuning of the undulator as well as to perform real time position tracking of magnet blocks, pulsed wire technique was adopted.

Novosibirsk free electron laser (FEL) facility contains three FELs operating in the wavelength range 8–240 micron at average power up to 0.5 kW and peak power about 1 MW. Radiation users works at 6 user stations performing biological, chemical, physical and medical research.

The concept of permanent-magnet variable-period undulator (VPU) was proposed several years ago and has found few implementations so far. The VPUs have some advantages as compared with conventional undulators, e.g., a wider range of radiation wavelength tuning and the option to increase the number of poles for shorter periods. Both these advantages will be realized in the VPU under development now at Budker INP. In this paper, we present the results of 2D and 3D magnetic field simulations and discuss some design features of this VPU.