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A new low-frequency CW RF gun was developed and tested at Budker Institute of Nuclear Physics recently. We plan to use it to upgrade the ERL of the Novosibirsk FEL facility. It will allow increasing the average beam current (due to higher beam repetition rate) and thus increasing the average radiation power. The transport beamline for the RF gun uses the ninety-degree achromatic bend. It is designed in a way that keeps an option to operate with the old electrostatic gun as well. Due to the low beam energy (290 keV) the beam dynamics is strongly influenced by space-charge forces. The paper describes results of simulation and optimization of the RF gun transport beamline. Space-charge forces were taken into account with the code ASTRA. Main sources of emittance degradation were considered in order to decrease their influence during the optimization. In addition, the RF gun output beam parameters were measured for various RF gun emission phases. These experiments were simulated and the results were compared. The resulting beam parameters meets requirements of the Novosibirsk FEL facility ERL., Proceedings of the 39th Free Electron Laser Conference, FEL2019, Hamburg, Germany

The undulator developed for the first FEL of Novosibirsk FEL facility employs variable-period structure based on the hybrid undulator scheme with poles splinted into halves. The design was adapted to deliver optimal performance, estimations were made based on results of three-dimensional field simulations. According to the modeling results, the undulator will not only widen significantly the first FEL tuning range moving the long-wavelength border of the first harmonic from 200 µm to 450 µm but also provide wider aperture and increase efficiency at shorter wavelengths., Proceedings of the 39th Free Electron Laser Conference, FEL2019, Hamburg, Germany

The first project of the four turn ERL for Novosibirsk FELs (NovoFEL) was proposed at FEL'90 Conference. Later the project was modified, but the base lines kept: a four turn normal conductance linac with energy recovery, low RF cavities (180 MHz), grid controlled DC gun (Q~1 nC, tau=1 nsec, f rep = 10 kHz-50 MHz). The ERL can operate in the three modes, providing an electron beam for the three different FELs (from 300 µm up to 5 µm). Construction and commissioning four track ERL was divided on three stage: the first stage NovoFEL working in spectral range (90-240) µm, based on one track energy recovery linac (ERL) with energy 12 MeV and current 30 mA, was commissioned in 2003. The second stage of NovoFEL working in spectral range (35-80) µm, based on two track energy recovery linac with energy 22 MeV and current 7 mA, was commissioned in 2009. The third stage of NovoFEL working in spectral range (8-15) µm, based on four track energy recovery linac with energy 42 MeV and current 5 mA was commissioned in 2015., Proceedings of the 59th ICFA Advanced Beam Dynamics Workshop on Energy Recovery Linacs, ERL2017, Geneva, Switzerland

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. As a source of electron bunches this FEL uses multi-turn energy recovery linac which has five straight sections. Three sections are used for three FELs which operate in different wavelength ranges (the first one - 90-240 microns, the second - 37-80 microns and the third - 5-20 microns). The first and the second FELs were commissioned in 2003 and 2009 respectively. They operate for users now. The third FEL is installed on forth accelerator track which is the last one and electron energy is maximal here. It comprises three undulator sections and 40 m optical cavity. The first lasing of this FEL was obtained in summer, 2015. The radiation wavelength was 9 microns and average power was about 100 watts. The designed power is 1 kilowatt at repetition rate 3.75 MHz. Radiation of third FEL has been delivered to user stations recently. The third FEL commissioning results as well as current status of the first and second FELs and future development prospects are presented., Proceedings of the 25th Russian Particle Accelerator Conf., RuPAC2016, St. Petersburg, Russia

The Novosibirsk FEL facility has three FELs, installed on the first, second and fourth orbits of the ERL. The first FEL covers the wavelength range of 90 - 240 mkm at an average radiation power of up to 0.5 kW with a pulse repetition rate of 5.6 or 11.2 MHz and a peak power of up to 1 MW. The second FEL operates in the range of 40 - 80 mkm at an average radiation power of up to 0.5 kW with a pulse repetition rate of 7.5 MHz and a peak power of about 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 wavelength range of 5 - 20 mkm. The Novosibirsk ERL is the first and the only multiturn ERL in the world. Its peculiar features include the normal-conductive 180 MHz accelerating system, the DC electron gun with the grid thermionic cathode, three operation modes of the magnetic system, and a rather compact (6×40 m2) design. The facility has been operating for users of terahertz radiation since 2004., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

A total of 77 magnets form the magnetic lattice of the BERLinPro energy recovery linac prototype: 1+8+8 dipole magnets of three different types, 12+40 quadrupole magnets of two different types and 8 sextupole magnets have been produced by BINP. After the design phase, magnets production started in 2015, measurements and delivery took place in 2016, first assembly stage was finished in 03/2017. The motivation for the magnet specification and a summary of the basic design is given in this paper. Select-ed measurement data from the final acceptance tests are presented and analysed to ensure the magnet quality., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

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., Proceedings of the 37th International Free Electron Laser Conference, FEL2015, Daejeon, Republic of Korea

To improve the parameters of the second stage Novosibirsk free electron laser one plans 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 for shorter periods with constant undulator length. Both these advantages will be realized in the new undulator under development in Budker INP. The idea of the permanent-magnet VPU was proposed just several years ago and it has not been properly tested yet. 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., Proceedings of the 37th International Free Electron Laser Conference, FEL2015, Daejeon, Republic of Korea