Traces of Stochasticity in Electron Trajectories in Gyrotron Resonators

The Hamiltonian approach is used to analyze the equation describing the electron interaction in gyrotron resonators with realistic RF field profiles. A detailed numerical study of the behavior of electron trajectories for some specific values of parameters controlling the interaction is performed. It is found that in some cases chaos-like motions of electrons are possible.     

Design of a 3-MW 140-GHz gyrotron with a coaxial cavity

A design for a 3-MW 140-GHz gyrotron based on the use of a coaxial cavity is given. The cavity mode is TE_21,13, chosen so that the ohmic heating on both the inner and outer conductors would be low enough for CW operation. The mode selection process, nonlinear, multimode and time-dependent modeling of the beam wave interaction, and gun design are discussed in detail. An inverted magnetron injection gun (MIG) is used to accommodate the inner conductor. The radiation is coupled out via a quasi-optical mode converter, consisting of an irregular cylindrical waveguide section followed by a step-cut launching aperture and a single near-parabolic mirror. The design of these components is also described     

Hysteresis in Mode Competition in High Power 170?GHz Gyrotron for ITER

Hysteresis in mode competition in high power 170 GHz gyrotrons for ITER is studied. Specific examples of hysteresis with respect to variation of magnetic field, current, electron beam radius and beam voltage are given.     

Are Coaxial Super Power Gyrotrons Feasible?

Limits on the power generated by coaxial gyrotrons are investigated. It is shown that among all the operating modes suggested recently for coaxial super power gyrotrons only modes with azimuthal index m lower than about 44 pass the spatial stochasticity test. Modes with higher azimuthal indices cannot be used as operating modes because gyrotron oscillations become chaotic in the azimuthal direction and efficiency is very low. It is argued that there exists a natural upper limit on power generated by gyrotrons which is about 4 MW.     

Determination of nuclear spectroscopic factors from data on differential cross sections for elastic neutron scattering on light nuclei

The values of the coupling constants (spectroscopic factors) dpn, ¹²C¹¹Cn and ¹⁴N¹³Nn have been derived by means of the extrapolation of differential cross section data to the corresponding poles. Some general questions concerning the application of this method to light nuclei are considered.     

Diagnostics of density fluctuations by enhanced scattering with frequency-tunable microwave sources

The enhanced scattering diagnostics method based on the scattering of microwaves close to the upper hybrid resonance in the plasma has a high sensitivity and spatial resolution and makes it possible to observe the plasma density fluctuations with characteristic scale-lengths much smaller than the wavelength of the probing radiation in vacuum. Good spatial resolution for spatial positioning of the scattering volume by fast tuning of the source frequency ±5% around the reference frequency in the range 100–300 GHz at high power makes this diagnostic method particularly suitable for fluctuation and high energy particle measurements in tokamak plasmas with relatively flat density and temperature profiles.     

Electron scattering with the excitation of the 15.11 MeV state of12C and theπ 12B12C coupling constant

Theπ ¹²B¹²C coupling constant is extracted from the data on theM1 form factor of¹²C using the PCAC and CVC hypotheses. The extrapolation of the form factor to the pion pole using analyticity arguments leads to the value \(f_{\pi ^{12} B^{12} C}^2 = 0.052\) . Our present knowledge of this coupling constant is discussed.     

The (π+π−), (π+ K −), (π− Σ+), (K + K −), and(\overline {\Sigma ^ + } \Sigma ^ + ) Atomic States

The expected energy shifts are calculated for the (π ⁺ π ^?), (π ⁺ K ^?), (π ^? Σ ⁺), and (K ⁺ K ^?) atomic states on the basis of the existing information on the corresponding scattering lengths.     

Pole and quark-counting model for form factors of light nuclei

The dispersion relation approach is applied to form factors of light nuclei. The form factor is approximated by a sum of poles. The asymptotic behaviour of form factor is assumed to be determined by quark-counting rule. Examples of³He,⁴He and⁶Li are considered. Data on form factors of these nuclei have been fitted with smaller number of parameters than usual, and corresponding charge distributions have been found which differ from conventional ones in central regions of nuclei.     

Eccentricity of the electron beam in a gyrotron cavity

Dependence of the coupling of the electron beam and RF field in a gyrotron cavity on eccentricity of the electron beam is studied.