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The experimental study of the quasi-optical mode convertor for 0.42THz, TE26 mode terahertz gyrotron has been carried out. The results show that the power conversion efficiency is more than 80%, and the gaussian content of the field at the output window is about 80%.
We have developed a calorimeter for a metrology standard for measuring the power of terahertz (THz) waves. Since the THz calorimeter is based on the thermal balance between heat produced by THz waves and direct current (DC), it requires an equivalent factor for converting from THz to DC power. The DC equivalent factor, which is defined as the ratio between the thermal efficiency of THz and DC powers,...
In this paper, we report the repeatability of calorimetric measurement of absolute terahertz (THz) power at room temperature. Highly sensitive measurement at a sub-microwatt level was performed by using a calorimeter based on an isothermal temperature-control technique. The experiment was demonstrated at 1 THz using a photomixer as a THz source. Type A uncertainty in repeatability was evaluated to...
The use of directed energy millimeter-waves to bore into hard rock is being investigated in the laboratory as an advanced drilling technology. Experiments at 28 GHz show that with peak intensities of 1–2 kW/cm2 granite, basalt, and limestone can be melted and vaporized to over 3000 °C in a few minutes. Heating is limited by radiative heat transfer loss. Key features for practical field implementation...
Terahertz (THz) photo-detectors, consisting of a r graphene nano-bridge and a plane antenna have been fabricated c and characterized. Hot electrons in graphene-bridge (GB) are generated after absorbing the incident THz photons. We measured the amplified thermal noise power from hot electrons to sense the absorbed THz power. By using this noise-thermometric technique, a THz photodetector with temperature...
Ocular temperatures during infrared or millimeter wave exposure were measured with thermography, fluoroptic thermometer, and microencapsulated thermochromic liquid crystals (MTLC) method. MTLC showed good correlation with ocular damage.
In the pursuit of an uncooled THz sensor, we address the specific modeling and optimization method for micro-machined transistors for the implementation of antenna-coupled MOSFET bolometers. We discuss the degrees of freedom for maximizing the device's SNR, outlining also the trade-offs in relation to the requirements of an integrated read-out circuit. The methodology was applied to novel antenna-coupled...
To provide stable output power of a gyrotron during long operation time the power stabilization was achieved by two schemes with PID feedback control of heater current and anode voltage. It was based on the dependence of the output power on both the anode voltage and the beam current and also on the dependence of the beam current on the gun heater current. Both schemes provided decrease of the power...
A Cyclotron Auto-Resonance Maser (CARM) is under study at the ENEA Research Laboratories in Frascati as a electron cyclotron heating (ECH) source in plasma magnetic confinement devices like Tokamaks. The aim of the project is the realization of a test source at 250 GHz to verify heating mechanisms in high magnetic field Tokamaks and at the second harmonics ECH frequencies for which a higher energy...
The upgraded Electron Cyclotron Resonance Heating (ECRH) system at ASDEX Upgrade (AUG) has been routinely used in the last experimental campaign. A further upgrade will replace an existing system of four short-pulse (140 GHz, 2s, 500 kW) gyrotrons. The final goal is to have around 6.5–7 MW at 140 GHz (or 5.5 MW at 105 GHz) from 8 units available in the plasma during the whole AUG discharge (10 s).
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