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The future EC systems will consist of several gyrotron sources providing MW-level millimeter wave power at a frequency around or above 170 GHz. The development of matched loads is necessary to test the new sources, the components for the transmission lines and the launchers, and must ensure high qualification for compatibility with the nuclear environment. The development at IFP-CNR and LTC of several compact high-power prototypes during the last decade led to a refinement of the overall design, resulting in the present low-reflectivity vacuum-compatible loads. The activity on loads is supported by F4E in view of the development of the EU gyrotron for ITER and required high-power tests at QST (Naka, Japan). Qualification is now supported by new tests at SPC (Lausanne, Switzerland) using the FALCON test-bed designed to test components and the EU gyrotron prototype for the EC system of ITER. These high-power tests, performed on the first CW prototype load (provided with 16 + 16 cooling channels in parallel) and shown in this paper, highlighted the need to improve the mechanical, vacuum and hydraulic design to reach the final goal of 1000s at ∼1 MW.

The future EC systems will consist of several gyrotron sources providing MW-level millimeter wave power at a frequency around or above 170 GHz. The development of matched loads is necessary to test the new sources, the components for the transmission lines and the launchers, and must ensure high qualification for compatibility with the nuclear environment. The development at IFP-CNR and LTC of several compact high-power prototypes during the last decade led to a refinement of the overall design, resulting in the present low-reflectivity vacuum-compatible loads. The activity on loads is supported by F4E in view of the development of the EU gyrotron for ITER and required high-power tests at QST (Naka, Japan). Qualification is now supported by new tests at SPC (Lausanne, Switzerland) using the FALCON test-bed designed to test components and the EU gyrotron prototype for the EC system of ITER. These high-power tests, performed on the first CW prototype load (provided with 16 + 16 cooling channels in parallel) and shown in this paper, highlighted the need to improve the mechanical, vacuum and hydraulic design to reach the final goal of 1000s at ∼1 MW. © 2018 Elsevier B.V.

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A spherical compact matched load, for high vacuum operation suited for short pulses (2MW. 0.1s.) precise measurement has been designed to test high power gyrotrons. In order to enhance the power handling capability of the load and to reduce the operation problems that may arise from an excessive reflection from the load a ray tracing code has been written to model the power distribution on the inner surface and the pattern of the reflected radiation. The outcome of this code has been used to select a more convenient profile for the spreading mirror of the load and to optimize a pre-load specially conceived to minimize the power reflected fraction.

The paper describes the design, calculation and performances of a fam-ily of calorimetric matched loads to be used with high power, millime-ter wave gyrotrons for ECRH applications in plasma physics. All the loads in the family are based on the same identical concept of a copper sphere coated on the inside with a partially absorbing ceramic layer. Different applications are foreseen, from a precise characterization of the e.m. beam power distribution in short pulses (up to 0.1 s), to the ab-sorption and calorimetric measure of beams at 2 MW, CW. The loads differ mainly in the way in which heat is removed, and calorimetry is performed.

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A plasma device with a cusp magnetic field configuration and operating under steady state condition has been built to investigate surface deposition of hydrocarbon films at low temperature and, simultaneously, the cracking of methane in a plasma environment to hydrogen production. The gas (methane or a methane/argon mixture) has been fed to the plasma source (a cylindrical capacitively coupled rf type). The addition of a static magnetic field has increased the particle confinement time and, consequently, the hydrogen production rate. Here the preliminary results concerning the growth of thin hydrocarbon films and the dissociation of methane in the cusp plasma are presented. In our case, at the line and point cusp, we have a large flux of energetic particles as well as neutral, ions, thermal radicals that participate in the growth process. A fraction of the converted methane has been deposited on the substrates, at the line cusp, as amorphous hydrocarbon (a-C: H) film and amorphous carbon (a-C) film. The surface morphology of the film has been observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) has been used to determine the structure of the film. The results have indicated that the film has a prevalently amorphous structure with a presence of crystalline clusters.

High-frequency wave systems with high-power density launching capability have been the Preferred choice to heat the Frascati Tokamak Upgrade (FTU) because of physics arguments (electron heating at very high density) and space constraints from the compactness of the machine design (8-cm-wide port). They do include an 8-GHz lower hybrid current drive (LHCD) system, a 140-GHz electron cyclotron resonance heating (ECRH) system, and a 433-MHz ion Bernstein waves system (IBW). The technical aspects of these systems will be reviewed in this article. The main features of the design include the following: (a) a very compact conventional LHCD grill with a compact window to keep the vacuum on 48 (12 columns, 4 rows) individual waveguides allowing the maximum flexibility in spectra generation to be achieved; power handling up to approximate to10 kW/cm(2) has been achieved, (b) ECRH launchers designed as a quasi-optical system (implementing ITER relevant solutions) retaining the maximum flexibility in the equatorial launcher (poloidal/toroidal steerability) to exploit a variety of scenarios, (c) a two-waveguides launching array making the IBW experiment on FTU unique. Other technical aspects (sources, transmission lines, etc.) are also reviewed. The development of a new ITER relevant lower hybrid launcher, the passive active multijunction, is described.

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Non transferred arc plasma torches are often used as plasma sources for the treatment of toxic and hazardous halogenated substances. At the IFP-CNR in Milan, a research program has been carried out for the development of some types of plasma torches with integrated waste injection systems. In this paper the electrical characterization of the Hollow Cathode Plasma Torch is studied. 1. Introduction The main

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