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Careful investigation of the RF oscillation frequency generated by MW class long-pulse 140 GHz gyrotrons for the Wendelstein 7−X (W7-X) stellarator found discrete frequency hopping in steps of 5–10 MHz during the initial frequency down-tuning as well as in long-pulse “quasi” steady-state operation. The classical explanation for this behavior, such as electron beam acceleration voltage ripple and the...
A short-pulse prototype tube has been designed and manufactured at KIT in order to support the development of the European 1MW, 170 GHz, CW gyrotron for ITER. The aim of the tests is the validation of the design of the most critical components, such as electron gun, cavity, beam tunnel and quasi-optical mode converter. First experimental results will be presented in this paper.
The TCV tokamak is presently undergoing major heating upgrades, installing a neutral beam for direct ion heating and increasing the electron cyclotron (EC) power injected in X-mode at the third harmonic (X3) and second harmonic (X2). The EC-system upgrade consists of adding two dual-frequency, 84/126 GHz, gyrotrons for X2 and X3 heating with a 1MW rf-power per gyrotron at both frequencies and 2s pulse...
In this paper we present preliminary results of the analysis on driving current and mitigating Neo-classical Tearing Mode instabilities, using Electron Cyclotron waves, as input for Port Plug development and integration in DEMO. The study has been carried out in a joint collaboration between the Karlsruhe Institute of Technology (Karlsruhe, Germany) and Max Planck Institute for Plasma Physics (Garching,...
Results of latest experimental studies on the frequency step-tunable (D-band) megawatt class gyrotron which is under development at IHM (KIT) are presented. The goal of the short pulse (∼ 1 ms) experiments was to study the performance of an upgraded cavity with longer cylindrical section. Target was to achieve significantly better efficiencies by introducing a cavity with a higher quality factor....
Under the umbrella of the EUROfusion Consortium and within the Power Plant Physics and Technology (PPPT) Conceptual Design Activities, the project Heating and Current Drive (H&CD) conducts a number of design activities and developments for a next generation clean and environmental friendly, long pulsed (∼2 hours) Demonstration fusion power plant (DEMO). This paper covers the results of the most...
Karlsruhe Institute of Technology (KIT) has started the development of gyrotrons for the first demonstration fusion power plant DEMO. A coaxial-cavity 238 GHz 2 MW gyrotron design is under investigation. After having obtained an initial cavity design, one focus of current studies is the associated triode-type magnetron injection gun (MIG). Constraints, design approaches and an initial gun design are...
The Demonstration Fusion Power Reactor (DEMO) to follow ITER by 2050 demands high frequency (>230 GHz), high power (in the range from 1 MW to 2 MW) gyrotrons as RF sources for electron cyclotron resonance heating and current drive (ECRH&CD). In the frame of the EUROfusion programme at KIT, the designs of conventional-cavity type and coaxial-cavity type DEMO-compatible gyrotrons are under investigation...
The development of the modular short-pulse pre-prototype as base for the 2 MW, 170 GHz, CW coaxial-cavity gyrotron for ITER upgrade and beyond is in progress at Karlsruhe Institute of Technology (KIT). The current modular pre-prototype configuration allows the generation of >2 MW RF output power in short-pulses with a reasonable electronic efficiency of approximately 30 % without depressed collector...
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).
Pultrusion is the process for production of semi-product composite profiles with carbon or glass fiber reinforcements [1], [2]. The glass or carbon fibers are mixed with resin (phenolic or epoxy) and pulled trough a shaping die. During this process heat is applied for curing the resin and getting a solid material. Today, conventional heating methods are used. At this place, a microwave applicator...
EU is presently developing a 1 MW, 170 GHz cylindrical cavity gyrotron for ITER. This activity was initiated in 2008 as a risk mitigation measure in parallel with the development of a 2 MW coaxial-cavity gyrotron, and in 2012 became the main line. In the previous year, the scientific designs of the 1 MW gyrotron components, such as the electron gun, beam tunnel, cavity, quasi-optical output coupler...
Parasitic beam tunnel oscillations have been hampering the series production of gyrotrons for W7-X. This problem has now been overcome thanks to the introduction of a specially corrugated beam tunnel. Two gyrotrons equipped with the new beam tunnel have fully passed the acceptance tests. Despite excellent power capability, the expected efficiency has not yet been achieved, possibly due to the presence...
The development of a 2 MW, 170 GHz short-pulse coaxial-cavity gyrotron pre-prototype for electron cyclotron heating and current drive (ECRH&CD) of magnetically confined plasmas in upcoming fusion devices is in progress at Karlsruhe Institute of Technology (KIT). Significant design modifications have been done recently. First experimental tests of a modified setup show two important unwanted effects...
Recent experimental results of the development of a frequency step tunable gyrotron suitable for continuous (CW) operation are presented. In recent experimental measurements a newly developed elliptically brazed CVD diamond Brewster window was tested in a short pulse regime up to 2 ms pulse length. It has been shown that the window is capable to transfer an RF-power of up to 1.3 WM operating in the...
Europe is making a significant joint effort to develop high power microwave sources (gyrotrons) for nuclear fusion applications. KIT is taking a large part in this. It is involved into the developments for W7-X and ITER, and it is starting research for gyrotrons which, in future, shall operate at multi-megawatt levels at above 200 GHz and shall allow step-frequency tunability. To enable this, KIT...
Europe is spending joint efforts to develop and to manufacture MW-level gyrotrons for electron cyclotron heating and current drive (ECRH&ECCD) of future plasma experiments. The two most important are the stellarator Wendelstein W7-X at Greifswald and the tokamak ITER at Cadarache. The construction of the 140 GHz, 1 MW CW gyrotrons for the 10 MW ECRH system of W7-X is proceeding well. It is expected...
Europe is spending significant joint efforts to develop and to manufacture MW-level gyrotrons for electron cyclotron heating and current drive (ECRH&CD) of future plasma experiments. The two most important are the stellarator Wendelstein W7-X at Greifswald [1] and the tokamak ITER at Cadarache [2]. While the series production of the 140 GHz, 1 MW, CW gyrotrons for the 10 MW ECRH system of stellarator...
In series production of new high power and high frequency gyrotrons the problem of beam alignment inside of cavity will become demanding, especially with the reduction of wavelength in future gyrotrons.
Using microwave heating allows for a fast and efficient volumetric heating. For chemical reactors microwaves permit to generate the heat inside the catalyst bed directly at the location where the reaction takes place. However, compared to conventional heating it is difficult to achieve a homogeneous temperature profile. At least for large scale applicators, which are not small in all dimensions compared...
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