Characteristics of ring resonator diplexers for high-power ECRH are briefly reviewed. Commissioning experiments performed on ASDEX Upgrade with the diplexer Mk IIa are presented, which demonstrate ...slow and fast switching of the power between two launchers, and thus the capability for efficient suppression of neoclassical tearing modes and simultaneous central heating of the plasma. The development of the compact diplexer Mk IIIb is discussed, and test results are presented. Finally, an evacuated design for 170 GHz is shown.
An off-the-shelf Phase-Locked Loop (PLL) system is used to stabilize the free-running oscillation frequencies of the 140 GHz, 1 MW CW gyrotrons of the companies Thales, France, and CPI, USA, that ...both operate at the ECRH system of the Wendelstein 7-X (W7-X) stellarator at IPP Greifswald, Germany. Both tubes are equipped with diode-type Magnetron Injection Guns (MIGs). Considering each of both type of gyrotrons as a Voltage Controlled Oscillator (VCO), each individual gyrotron is controlled by the variation of the body voltage. The results of the experiments demonstrate the capability of the developed and implemented inexpensive off-the-shelf PLL system. It is possible to stabilize the oscillation frequency within a full -20 dB bandwidth of < 100 kHz. Applications such as Collective Thomson Scattering (CTS) systems to accurately diagnose the ions in fusion plasmas could benefit from this development in future.
The progress of industrial gyrotron developments at Thales, that are done in collaboration with its European partners, are presented in this report. Recent test results are discussed and the design ...status of new industrial units under development is presented.
ECRH at W7-X - Concurrent Operation of 10 Gyrotrons Braune, H.; Brunner, K.J.; Laqua, H. P. ...
2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz),
2018-Sept.
Conference Proceeding
At the stellarator Wendelstein 7-X (W7-X) Electron Cyclotron Resonance Heating (ECRH) is the main heating system for steady-state operation and was the only available heating system during the ...operation phase OP1.2a in 2017. The ECRH, equipped with 10 operational 140 GHz gyrotrons 1, was used for different tasks at W7-X such as wall conditioning, controlled plasma start-up from the neutral gas up to steady state plasma control and different heating scenarios such as X2-mode and O2-mode heating as well as current drive (ECCD). The achieved plasma parameters with respect to the performance of the ECRH plant will be discussed.
Electron Cyclotron Resonance Heating (ECRH) is the main heating system for steady-state operation and was the only available heating system during the first operational phase (OP1.1) of the W7-X ...stellarator 1. The ECRH was used for different tasks at W7-X such as wall conditioning, controlled plasma start-up from the neutral gas up to steady state plasma control 2 and performance optimization by temperature profile shaping. The ECRH plant was equipped with 7 gyrotrons and 6 of them were operational. The quasi optical transmission line was precisely adjusted in preparation of OP1.1. The operational experience of the ECRH plant will be discussed.
Repeated low doses of streptozocin (STZ; 40 mg/kg, 5 injections/day) induce hyperglycemia in certain strains of mice after a latency of 1 wk. Omega-3 polyunsaturated fatty acids (omega 3FA) have been ...reported to suppress immune processes by blockade of the cyclooxygenase pathway of arachidonic acid metabolism. We investigated the effects of diets high in omega 3FA on the development of diabetes in the low-dose STZ-induced diabetes (LDSTZ-D) model. Male C57BL/6J mice were on a fish oil diet (FOD) as a source of omega 3FA 8 wk before STZ injection. Controls received laboratory chow only or a coconut oil diet (COD). Blood glucose levels in FOD mice were reduced (12.5 vs. 28 mM for COD mice, P less than .001) 60 days after STZ injection with a diet in which 20% of the calories were from fish oil. In FOD mice, immunohistology showed reduced numbers of class II antigen-expressing cells in pancreatic islets followed by a decreased extent of insulitis. FOD significantly decreased the number of Fc receptor-negative dendritic cells in cytospin preparations of islets isolated from diabetic mice. Interleukin 1-like activity of peritoneal exudate cell supernatants isolated from mice on FOD was reduced. FOD did not improve insulin secretion of isolated islets from LDSTZ-D mice. These data indicate a beneficial effect of FOD on the immune component of the mouse LDSTZ-D model.
The xenon spectrum, excited in ECR- and NBI-heated plasmas with central electron densities of around 10 m, and central electron temperatures from 0.7 to 2.5 keV, has been studied photoelectrically ...with a multi-channel grazing-incidence spectrometer. Besides numerous well-known lines of Zn- and Cu-like Xenon, more than 50 additional lines which have not yet been published in the literature have been found and partly identified,.
A new CW-load for high power ECRH systems Braune, H.; Erckmann, V.; Hollmann, F. ...
2011 International Conference on Infrared, Millimeter, and Terahertz Waves,
2011-Oct.
Conference Proceeding
Plasma heating at upcoming thermonuclear fusion experiment facilities will be partially performed by large Electron Cyclotron Resonance Heating (ECRH) installations. The required pulse length is 1000 ...seconds (ITER specification) and more in order to meet the physical aims at Stellarators and Tokamaks as well. The conditioning and testing of the ECRH sources, high power gyrotrons, is an important task of these installations. CW operation under full power conditions requires a microwave load with a power level in the range of 1 MW. In the ECRH system at W7-X several types of loads are in operation but their long term stability needs to be improved. A new approach of load design will be discussed which is currently under test.
Extended operation of the 1 MW, CW gyrotrons for W7-X Braune, H.; Brand, P.; Dammertz, G. ...
2007 Joint 32nd International Conference on Infrared and Millimeter Waves and the 15th International Conference on Terahertz Electronics,
2007-Sep.
Conference Proceeding
Electron Cyclotron Resonance Heating (ECRH) is the main heating method for the Wendelstein 7-X Stellarator (W7-X), which is under construction at IPP- Greifswald. A 10 MW ECRH plant with ...CW-capability at 140 GHz is under construction to meet the scientific objectives. The microwave power is generated by 10 gyrotrons with 1 MW each. Three gyrotrons are already operational at IPP in Greifswald. The W7-X gyrotrons are designed for single frequency operation at 140 GHz. The operation regime of the W7-X stellarator experiments is restricted to magnetic fields matched to the ECRH-frequency and it would be interesting to extend the operation regime to a second resonant magnetic field. Therefore gyrotron operation at a second frequency was investigated. The standard vertical collector sweep systems of gyrotrons inherently display a pronounced peaking of the collector heat loading. An improved collector sweep system was successfully tested on the TED gyrotrons, which creates an almost homogenous heat loading. This system is of particular interest for next generation gyrotrons with an output power up to 2 MW.
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