Search results for "Hertz"
showing 10 items of 177 documents
Experimental verification of a self-consistent calculation for continuous frequency-tune with a 400 GHz band second harmonic gyro-BWO
2013
A self-consistent code is introduced to develop a continuous frequency tunable gyro-BWO. A cavity is designed with TE8,5 mode for 400 GHz band second harmonic oscillation. The experimental verification has been carried out and 2 GHz tunability is observed with output powers of higher than 40 W.
Influence of possible reflections on the operation of European ITER gyrotrons
2010
The theory describing the influence of reflection s on operation of gyrotrons with radial output is used for evaluating the effect of reflections on the operation of the ITER 170 GHz 2 MW coaxial cavity gyrotron, which is under development, and the 170 GHz 1 MW cylindrical cavity gyrotron as a fall back solution.
Gyrotron Operation in the ‘No-Start-Current’ Zone
2018
It is conventionally assumed that the gyrotrons can operate either in the regime of soft self-excitation, where the beam current exceeds the start current, or in the regime of hard excitation, where the beam current is lower than the start current. The authors have found one more possibility of gyrotron operation: in the region where there is no start current at all. Although it is not clear whether this region represents a special interest for gyrotron operation, it can be useful to learn that such opportunity may exist and can be used for interpreting some experimental results.
Physical principles of the amplification of electromagnetic radiation due to negative electron masses in a semiconductor superlattice
2015
In a superlattice placed in crossed electric and magnetic fields, under certain conditions, the inversion of electron population can appear at which the average energy of electrons is above the middle of the miniband and the effective mass of the electron is negative. This is the implementation of the negative effective mass amplifier and generator (NEMAG) in the superlattice. It can result in the amplification and generation of terahertz radiation even in the absence of negative differential conductivity.
Amplification of nonlinear currents generation at harmonics frequencies of submillimeter radiation
2006
The conditions are found when rapid heating of the electrons of a degenerate semiconductor in the presence of two electric fields, one constant and the other variable, is accompanied by the formation of a distribution function significantly departing from the Fermi one. It is also shown that the newly found modification of the electron distribution yields a relative amplification of nonlinear currents generation.
The rotational spectrum of 17O2 up to the THz region
2016
Abstract The investigation of the pure rotational spectrum of the 17O2 isotopic species of molecular oxygen has been extended with respect to previous investigations to the submillimeter-wave region, from 230 GHz up to 1.06 THz. The resulting spectroscopic parameters, which have an accuracy comparable to that of the constants obtained from an updated isotopic invariant fit involving data for three electronic states and six isotopologues [Yu et al. High resolution spectral analysis of oxygen. IV. Energy levels, partition sums, bandconstants, RKR potentials, Franck–Condon factors involving the X 3 Σ g − , a 1 Δ g , and b 1 Σ g + states. J Chem Phys 2014;141:174302/1–12], permit the prediction…
High Cyclotron Harmonics Excitation in Multi-beam Terahertz Range Gyrotrons
2019
The paper presents recent results on the multi-beam gyrotrons operating at cyclotron harmonics in terahertz frequency range. The theoretical and experimental investigation of second harmonic 0.78 THz gyrotron includes comparison of generating and absorbing beam schemes, research on the effect of velocity spread and mode competition process, along with development of third harmonic 1.2 THz tube based on verified numerical codes and latest experimental results.
Are Coronae of Late‐Type Stars Made of Solar‐like Structures? The X‐Ray Surface Flux versus Hardness Ratio Diagram and the Pressure‐Temperature Corre…
2004
This work is dedicated to the solar-stellar connection, i.e., the close similarity of the Sun and late-type stars; in particular, this work shows that stellar coronae can be composed of X-ray-emitting structures similar to those present in the solar corona. To this end we use a large set of ROSAT PSPC observations of late-type stars of all spectral types and activity levels and a large set of solar X-ray data collected with Yohkoh SXT. Solar data have been analyzed and formatted to study the Sun as an X-ray star; they include observations of the solar corona at various phases of the solar cycle and data on various kinds of X-ray coronal structures, from flares to the background corona, i.e.…
AB Doradus C: age, spectral type, orbit, and comparison to evolutionary models
2005
We expand upon the results of Close et al. 2005 regarding the young, low-mass object AB Dor C and its role as a calibration point for theoretical tracks. We present an improved spectral reduction and a new orbital solution with two additional epochs. Our improved analysis confirms our spectral type of M8 (+/- 1) and mass of 0.090+/-0.003 solar masses for AB Dor C. Comparing the results for AB Dor C with other young, low-mass objects with dynamical masses we find a general trend where current evolutionary models tend to over-predict the temperature (or under-predict the mass) for low mass stars and brown dwarfs. Given our precision, there is a ~99% chance that the mass of AB Dor C is underes…
Gas-phase detection of discharge-generated DSOD
2003
Abstract We report the first spectroscopic detection of perdeuterated 1-oxadisulfane, DSOD, generated in a radio-frequency plasma of D2S and D2O. The chain molecule DSOD produces a perpendicular-type spectrum, with well-known spectral features encountered in previous studies of geometrically related molecules, such as compact Q-branches, which are clearly recognizable. The arrangement of the transitions shaping the Q-branches usually provides sufficient proof for a clear-cut detection of a chain molecule such as DSOD. Guided by quantum chemical calculations, we have located the band center of the r Q 2 -branch of DSOD in the frequency region near 466.5 GHz using the Cologne terahertz spectr…