- Physicist Professor in ElectronicsPlasma and AstrophysicistDiamond Technologyedit
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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... more
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 of EGYC. Moreover, as part of EUROfusion, KIT is investing in the research for advanced fusion gyrotrons of future EU DEMO. The target is to develop gyrotrons which will fulfil the need for RF sources operating at a frequency above 200 GHz, an RF output power above 2 MW and a total efficiency above 60 %. Aditionally, multi-purpose/multi-frequency operation and frequency step-tunability are requested. That requires the research and development on advanced gyrotrons, test environments and control techniques. This contribution provides a view over ongoing and planned activities in the field of gyrotron development at KIT.
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ABSTRACT The ITER Electron Cyclotron Heating and Current Drive (ECH&CD) Upper Launcher, whose preliminary design was approved in 2009, is on its way towards the final design. The design work is being done by a consortium of... more
ABSTRACT The ITER Electron Cyclotron Heating and Current Drive (ECH&CD) Upper Launcher, whose preliminary design was approved in 2009, is on its way towards the final design. The design work is being done by a consortium of several European research institutes in tight collaboration with F4E. The main focus is the finalization of the design of all components for the First Confinement System (FCS), which forms the vacuum and Tritium barrier. The FCS comprises structural components as well as the external waveguide components in the port cell. Structural components of the FCS include the flange seal, backend frame and closure plate. The external waveguide components include the isolation valve, CVD diamond windows, miter bends and straight waveguides. Because finalizing of the design of these components is directly influenced by the layout of many in-vessel components, the design work includes also further development of the entire launcher. This paper summarizes the most recent status of the design work on the structural components of the launcher FCS, which are the support flange, the socket, the closure plate and feed-throughs for waveguides and cooling pipes. The design work includes the engineering layout of these components in accordance with system requirements, load specifications and Quality and Safety classification. An outline of the overall design of the launcher will be presented. The design progress was based on a set of related analyses, of which particular results are given. Also the integration of the associated mm-wave components, assembly strategies, neutronic aspects and the design of the shielding components will be described.
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Four ECH Upper Port Plugs are foreseen at ITER for counteracting plasma instabilities based on the injection of up to 20 MW mm-wave power at 170 GHz into the plasma. The required targeting of flux surfaces will be achieved by angular... more
Four ECH Upper Port Plugs are foreseen at ITER for counteracting plasma instabilities based on the injection of up to 20 MW mm-wave power at 170 GHz into the plasma. The required targeting of flux surfaces will be achieved by angular steering in the poloidal direction. The paper describes the main components of the mm-wave and structural system for the
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ABSTRACT The design of the ITER Electron Cyclotron Heating and Current Drive (ECH&CD) Upper launcher is recently in the first of two final design phases. The first phase deals with the finalization of all FCS (First... more
ABSTRACT The design of the ITER Electron Cyclotron Heating and Current Drive (ECH&CD) Upper launcher is recently in the first of two final design phases. The first phase deals with the finalization of all FCS (First Confinement System) components as well as with specific design progress for the remaining In-vessel components. The most outstanding structural In-vessel component of an ECH&CD Upper launcher is the Blanket Shield Module (BSM) with the First Wall Panel (FWP). Both of them form the plasma facing part of the launcher, which has to meet strong demands on dissipation of nuclear heat loads and mechanical rigidity. Nuclear heat loads from 3 MW/m3 at the First Wall Panel’ surface, decaying down to a tenth in a distance of 0.5 m behind of it will affect the BSM and the FWP. Additional heating of maximum 0.5 MW/m2 due to plasma radiation must be dissipated from the FWP. To guarantee save and homogenous removal of such extensive heat loads, the BSM is designed as a welded steel-case with specific cooling channels inside its wall structure. Attached to its face side is the FWP with a high-power cooling structure. Based on computational analysis the optimum cooling channel geometry has been investigated. Specific pre-prototype tests have been made and associated assembly parameters have been determined in order to identify optimum manufacturing processes and joining techniques, which guarantee a robust design with maximum geometrical accuracy. This paper describes the design, manufacturing and testing of a full-size mock-up of the BSM. The study was carried out in an industrial cooperation with MAN Diesel and Turbo SE.
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ABSTRACT RSFQ-toggle-flipflops with a SFQ-trigger circuit a Josephson transmission line at the input and a SFQ/dc-circuit at the output of each stage are implemented in the Nb–Al2O3–Nb Josephson junction technology on a single chip having... more
ABSTRACT RSFQ-toggle-flipflops with a SFQ-trigger circuit a Josephson transmission line at the input and a SFQ/dc-circuit at the output of each stage are implemented in the Nb–Al2O3–Nb Josephson junction technology on a single chip having coplanar wave guides at input and output. The counter is tested successfully at 4.2K via coplanar/coaxial transitions using a bit pattern generator and a digital oscilloscope at room temperature up to fI≈2GHz pulse repetition frequency at the input. The highest test frequency fI is limited by the available pattern generator.
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ABSTRACT In this paper, we present first measurements, carried out at microwave wavelengths, aiming to characterize the dielectric properties of large size single crystalline diamond (SCD) wafers. While the sizes of the SCD wafers are... more
ABSTRACT In this paper, we present first measurements, carried out at microwave wavelengths, aiming to characterize the dielectric properties of large size single crystalline diamond (SCD) wafers. While the sizes of the SCD wafers are still not sufficient for practical use, we obtained good optical properties results. The sample with both sides polished shows a dielectric loss tangent tanδ as low as or possibly lower than a polycrystalline diamond sample with high quality. Results show the importance of surface treatment, especially on the boundaries of the composed SCD chips even without any graphitic component in the diamond wafers.
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ABSTRACT
The multi-frequency Electron Cyclotron Heating (ECRH) system at the ASDEX Upgrade tokamak employs depressed collector gyrotrons, step-tunable in the range 105-140 GHz. The system is equipped with a fast steerable launcher allowing for... more
The multi-frequency Electron Cyclotron Heating (ECRH) system at the ASDEX Upgrade tokamak employs depressed collector gyrotrons, step-tunable in the range 105-140 GHz. The system is equipped with a fast steerable launcher allowing for remote steering of the ECRH beam during the plasma discharge. The polarization can be controlled in a feed-forward mode.
A multi-frequency Electron Cyclotron Heating (ECRH) system is in operation at the ASDEX Upgrade tokamak, currently employing three depressed collector gyrotrons, operating at 105 and 140 GHz. The system offers a high flexibility for a... more
A multi-frequency Electron Cyclotron Heating (ECRH) system is in operation at the ASDEX Upgrade tokamak, currently employing three depressed collector gyrotrons, operating at 105 and 140 GHz. The system offers a high flexibility for a variety of plasma heating and current drive experiments including remotely controlled fast beam steering and modulation.
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... They can be integrated easily in rf circuits and allow acceptable properties at 77 K [8,9]. The phase shifter allows for rather large tolerances of the maximum Josephson current and can therefore be implemented with the present state... more
... They can be integrated easily in rf circuits and allow acceptable properties at 77 K [8,9]. The phase shifter allows for rather large tolerances of the maximum Josephson current and can therefore be implemented with the present state of technology. Fabrication ...
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ABSTRACT
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ABSTRACT A device on a single 2"-LaAlO 3 wafer for a four bit instantaneous frequency measurement between 9.5 GHz and 10.5 GHz has been developed with coplanar Y 1 B 2 Cu 3 O 7-d d delay lines and power dividers. Compared to... more
ABSTRACT A device on a single 2"-LaAlO 3 wafer for a four bit instantaneous frequency measurement between 9.5 GHz and 10.5 GHz has been developed with coplanar Y 1 B 2 Cu 3 O 7-d d delay lines and power dividers. Compared to known triplate strip lines, coplanar delay lines are easier to fabricate monolithically and allow for a greater flexibility in the circuit design. Simulated and measured results are in good agreement. I. INTRODUCTION A 5 bit instantaneous frequency measurement (IFM) subsystem for a bandwidth of 500 MHz and a center frequency of 4 GHz has already been implemented with Y 1 Ba 2 Cu 3 O 7-d delay lines on LaAlO 3 substrates [1]. The 5-way power divider and each of the 5 discriminators have been fabricated separately and placed in 6 massive aluminum subpackages. Delays up to 16 ns have been achieved with striplines in dual-spiral form comprising two 508 m thick LaAlO 3 substrates pressed together. Each discriminator had a microstrip Wilkinson power divider [2] an...
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CVD diamond is a well known excellent low loss material (tan δ ≤ 10−5) for microwave transmission e.g. in fusion reactors for the ECRH&CD system. Laser processing of diamond discs allows the artificial formation of grooves on diamond disc... more
CVD diamond is a well known excellent low loss material (tan δ ≤ 10−5) for microwave transmission e.g. in fusion reactors for the ECRH&CD system. Laser processing of diamond discs allows the artificial formation of grooves on diamond disc surfaces. A potential application is the design of windows with a surface finish offering an increased bandwidth. As grooves with sharp edges and corners might lead to local stress accumulation beyond tolerable limits, the method has been checked by FEM analyses. The results are here summarized.
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ABSTRACT Seven gyrotrons are currently in operation in the ASDEX Upgrade Electron Cyclotron Resonance Heating (ECRH) system delivering a total of 3.9 MW to the plasma at 140 GHz. The 3 new gyrotrons are capable of 2-frequency operation... more
ABSTRACT Seven gyrotrons are currently in operation in the ASDEX Upgrade Electron Cyclotron Resonance Heating (ECRH) system delivering a total of 3.9 MW to the plasma at 140 GHz. The 3 new gyrotrons are capable of 2-frequency operation and may heat the plasma alternatively with 2.1 MW at 105 GHz.
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NTRODUCTION J u n c ti o n s a l o n g a g r a i n bo u n d a r y o f t h e s u b s t r a t e a r e v e r y p r o mi s i n g f o r f