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Two gyrotrons have recently been installed in the multi-megawatt Electron Cyclotron Resonance Heating (ECRH) system at the ASDEX Upgrade (AUG) tokamak. They are part of a new system that replaces an older ECRH system which was operating since 1996. The new two-frequency gyrotrons operating at AUG at 105 and 140 GHz (10 s pulse length with output powers close to 1 MW) are part of an upgrade with four...
Karlsruhe Institute of Technology (KIT) is doing research and development in the field of high power gyrotrons for W7-X, ITER, and, towards a future DEMOnstration fusion power plant. While the initial installation of the ECRH system at W7-X is finished and operating very successfully, KIT is still involved in the development of gyrotrons for ITER. This work is coordinated by F4E and ongoing in frame...
Research is continuing to improve the performance of a 2 MW CW RF load for gyrotrons and electron cyclotron heating systems. Efforts are focused on reducing reflected power and cost. The load is designed to dissipate more than 2 MW CW of RF power, and recent tests demonstrated the power capability exceeds 1.7 MW.
Determining the absorption of MMW in living tissue is a complex problem due to tissue inhomogeneity. As the sample size and tissue elementary structural unit becomes smaller, e.g. single cells, the measurements with contemporary techniques get more challenging. Also, MMW and THz radiation can affect the functionality of the biological sample, thus changing its response. However, these changes can...
By utilizing a scattering-type scanning near-field optical microscope (s-SNOM) in mid-infrared (mid-IR) region, we studied nanoscale optical and thermal properties of the nanoporous graphene, that is an emerging type of carbon material. Nanoscale IR images revealed that the strained graphene near the nanopores emits less heat radiation, suggesting different absorption mechanism. The present findings...
Calabazas Creek Research, Inc. is developing a compact, inexpensive broadband system that replaces the external matching optical unit for coupling RF power from MW-class gyrotrons into transmission lines. A critical component is a Brewster window in HE11 waveguide. This paper describes progress in fabricating and testing critical components.
A mathematical model of heating a biological tissue with electromagnetic radiation is suggested in this research. The dependence of heating the biological tissue on various modes of generation and radiative powers is constructed. Thermal and physical coefficients of a porcine eye cornea were experimentally determined. It was demonstrated that the 100μW of radiative power deposition can heat the biological...
We performed terahertz time-domain spectroscopy on glassy glucose, and successfully detected the boson peak, which is a universal feature of glassy materials. In addition, we have experimentally determined the infrared-vibration coupling coefficient (CIR(v)) using the vibrational density of states. The obtained CIR(v) shows linear frequency-dependence and the behavior deviates from the inorganic glass...
A set of two corrugated polarizer mirrors is typically used in high-power Electron Cyclotron Resonance Heating (ECRH) systems to provide the required polarization of the ECRH output beam. The ohmic losses of these mirrors can significantly exceed the losses of plane mirrors depending on the polarization of the incident beam with respect to the orientation of the grooves. Since polarizer mirrors incorporated...
We show the first experimental result of direct hot electron imaging by scanning the local ultra-high frequency 21 terahertz, THz) shot noise at room temperature. In nonequilibrium situations, the local fluctuation of current-carrying electrons (known as shot noise) contains fingerprint-like information of electron kinetics. We use a sharp tungsten tip as a movable, contact-free noise probe to locally...
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