Demonstrating high-power 30-GHz free-electron maser operation on a resonant load

Peculiarities of the Mode Spectrum in Free-Electron Masers Based on Oversized Bragg Resonators with a Corrugation Phase Step

“…Modeling shows [19,20] that this regime is optimal from the viewpoint of reducing the sensitivity to the parameter spread of relativistic electron beams and, correspondingly, achievement of a high electronic efficiency. This was confirmed in the previous experimental studies of the FEM oscillator [1,2].…”

“…However, it is also shown below that in the oversized resonator the neighboring Bragg zones affect the mode spectrum even if these zones are frequency separated. 1 Assume that two waveguide modes E 1 and E 2 with different transverse structures participate in the scattering and represent the field in the Bragg structure in the form of four partial waves:…”

“…The main requirement to this source of radiation is provision of a high pulse power and stable narrow-band oscillation. To achieve the indicated parameters in the FEM oscillator developed at the JINR and IAP RAS [1,2], the inverse guiding magnetic field regime was used for the first time [3,4]. A Bragg resonator in the form of two sections of a corrugated waveguide with the corrugation phase jump π at the place of their conjunction (the so-called corrugation phase-jump resonator, see Fig.…”

Equilibrium electrons in free-electron lasers with a 3D helical wiggler and a guide magnetic field: Nonlinear simulations

“…Nevertheless, it evidently indicates that the electron motion in a positive guide magnetic field gets a greater fluctuation than that in a reversed guide magnetic field, especially in the adiabatic region of the 3D helical wiggler. Figure 3(b) presents a comparison of the motion stability of the test electrons with initial on-axis and off-axis guiding centers in the case of a reversed guide magnetic field, where the parameters are from the JINR experiment [21]: the wiggler had a period w ¼ 6 cm, a field magnitude B w ¼ 1000 G, a length L w ¼ 216 cm, and an adiabatic period number N w ¼ 6; the electron beam had an average energy factor 0 ¼ 2:6, a current I b ¼ 200 A, and a radius R b ¼ 0:4 cm; the waveguide had a radius R w ¼ 0:95 cm. It is clear from the figure that after passing through the adiabatic region of the wiggler, the test electrons' motion is stable and motion fluctuation is small, no matter if the initial guiding center is on axis or off axis.…”

Powerful narrow-band relativistic masers with Bragg resonators operating from mm to sub-mm wavelength band: resent results and prospects

“…By now, powerful narrow-band free-electron maser (FEM) operating at mm wavelength band has been realized in collaboration between JINR (Dubna) and IAP RAS (N.Novgorod) [1]. The radiation parameters achieved allows JINR-IAP FEM to be used in several applications including testing of components for highgradient accelerators, biology-medical studies, physics of nanoparticles, etc [2].…”