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We demonstrate here an efficient THz source with low electrical power consumption. We have also overcome the saturation problem in THz sources at higher applied bias voltages by irradiating the SI-GaAs source substrate crystals with energetic Carbon ions. Photoconductive Emitter (PCE) source fabricated on an un-annealed Carbon irradiated SI-GaAs has shown linear increase in emitted THz Electric field...
This paper presents a method for estimation of junction temperature of a Schottky diode used in a recently developed frequency doubler to 332 GHz. Our particular interest was the validation of the thermal model of the diode by comparison of the simulated junction temperature with the real junction temperature under operating conditions. RF operating condition is here artificially simulated by dissipating...
Hydration and dehydration processes during a pharmaceutical granulation process of xanthine related compounds were investigated using terahertz/far-infrared, mid-infrared and near-infrared electromagnetic waves. Certain kinds of xanthine related compounds and binders gave hydration and/or dehydration.
Sensitive millimeter wave diagnostics need often to be protected against unwanted radiation like, for example, stray radiation from high power Electron Cyclotron Resonance Heating applied in nuclear fusion. A notch filter based on a waveguide Bragg reflector (photonic bandgap) can provide several stop bands of defined width within up to two standard waveguide frequency bands.
We report the terahertz spectrum of a high birefringence liquid crystalline mixture 2002 from 0.2 to 1.6 THz, using terahertz time domain spectroscopy (THz-TDS). Furthermore, the phase transition from nematic to isotropic phases was observed using temperature-dependent THz-TDS.
Heating and Current Drive systems are of outstanding relevance in fusion plasmas, magnetically confined in tokamak devices, as they provide the tools to reach, sustain and control burning conditions. DEMO, and the future reactor will require higher frequency for ECH. Therefore, high power (≥1MW) RF sources with output frequency in the 200 – 300 GHz range would be necessary.
A new 154GHz/ 1MW gyrotron was developed and installed in the Electron Cyclotron Resonance Heating system of LHD. The maximum output power of 1.16MW/ 1sec was achieved. Total injected power into a plasma reached 4.4MW with the existing three 77GHz gyrotrons' power. The 154GHz gyrotron contributed to extend the plasma parameters to higher temperature and density region.
Terahertz (THz) absorption spectra of supramolecular gels ((1R,2R)-1,2-bis(dodecanoylamino)cyclohexane / 2-nitrophenyl octyl ether) were measured by Fourier transform far-infrared spectroscopy (FT-FIR). The spectra were measured by changing concentration and temperature of gels. The absorption intensities of the peaks around 8.6 THz show drastic change at the sol-gel transition temperature.
The W7-X start-up scheduled for 2015 demands a lot of integrated tests at all auxiliaries as well as the ECRH installation in order to ensure a reliable interaction. Up to 10 gyrotrons have to be controlled as well as 10 different wave guides and two additional remote steering launchers apart from the 10 ordinary front steering launchers. The ECRH remote control system has to be connected to the central...
A Microelectromechanical system (MEMS) cantilever pressure sensor was designed, modeled, fabricated, and tested for sensing the photoacoustic response of gases to Terahertz (THz) radiation. This paper describes manufacturing, experimental set-up and the most recent spectroscopic results, which demonstrate the capabilities of this spectroscopic technique.
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