The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
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...
A multi-megawatt Electron Cyclotron Resonance Heating (ECRH) system is in routine operation at the ASDEX Upgrade (AUG) tokamak. It applies four step-tunable gyrotrons at 105 and 140 GHz with 10 s pulse length and output powers close to 1 MW. An upgrade with four more gyrotrons is underway which will double the installed power. The first two-frequency gyrotron of the new series has recently been installed...
The upgraded electron cyclotron resonance heating (ECRH) system at ASDEX Upgrade (AUG) has been routinely used with eight gyrotrons during the last experimental campaign. A further upgrade will replace the existing system of four short-pulse (140 GHz, 2 s, 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 eight units available in the plasma during...
Photonic Bandgaps (Bragg reflectors) in moderately oversized corrugated waveguides can be applied as notch filters in the mm and sub-mm wavelength range. They offer unique options such as very steep frequency slopes, narrow or wide stop bands and very low insertion loss when compared to other technologies such as coupled cavity or Fabry-Pérot type filters. Also several defined stop bands within one...
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).
Sensitive millimeter wave diagnostics need often to be protected against unwanted radiation like, for example, stray radiation from high power Electron Cyclotron Resonance Heating applied in nuclear fusion. A notch filter based on a waveguide Bragg reflector (photonic bandgap) can provide several stop bands of defined width within up to two standard waveguide frequency bands.
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.
Notch filters are required to protect sensitive millimeter wave diagnostics in fusion experiments from gyrotron stray radiation in the plasma vessel. A new type of notch filter based on a waveguide Bragg reflector is presented that can provide several defined stop bands in one standard waveguide frequency band.
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.
Indexing quickly and accurately in a large collection of images has become an important problem with many applications. Given a query image, the goal is to retrieve matching images in the collection. We compare the structure and properties of seven different methods based on the two leading approaches: voting from matching of local descriptors vs. matching histograms of visual words, including some...
Recent few years a multi-frequency gyrotron for modernization of ASDEX Upgrade ECRH system is under development in GYCOM/IAP by contract with IPP. Following contract specifications the gyrotron must produce 10-s pulses with 1MW output power at 140GHz and over 800-kW power at 3 additional frequencies within 105-140GHz frequency range. The gyrotron output window is to be transparent for radiation in...
Gathering a large collection of images has been made quite easy by social and image sharing websites, e.g. flickr.com. However, using such collections faces the problem that they contain a large number of duplicates and highly similar images. This work tackles the problem of how to automatically organize image collections into sets of similar images, called image families hereinafter. We thoroughly...
A new ECRH system is currently under construction at the ASDEX Upgrade tokamak. It employs for the first time depressed collector gyrotrons, step-tunable in the range 105-140 GHz. In its final stage it will consist of 4 gyrotrons with a total output power of 4 MW and a pulse length of 10 s. In this paper we describe recent extensions of the system and some experimental results.
Gathering large collections of images is quite easy nowadays with the advent of image sharing Web sites, such as flickr.com. However, such collections inevitably contain duplicates and highly similar images, what we refer to as image families. Automatic discovery and cataloguing of such similar images in large collections is important for many applications, e.g. image search, image collection visualization,...
Currently, a new multi-frequency ECRH system is under construction at the ASDEX Upgrade Tokamak experiment. This system employs, for the first time in a fusion device, multi-frequency gyrotrons, step-tunable in the range 105-140 GHz. The system includes fast steerable launchers at the front end that will allow for very localized feedback controlled power deposition in the plasma.
Summary form only given. A multi-frequency ECRH system is currently under construction at the ASDEX Upgrade tokamak experiment. The system employs depressed collector gyrotrons, step-tunable in the range 105-140 GHz, with a maximum output power of 1 MW and a pulse length of 10 s. One two-frequency GYCOM gyrotron is in routine operation at ASDEX Upgrade since 2006. A further extension of the system...
Summary form only given. The first two-frequency GYCOM gyrotron Odissey-1 has been installed and put into operation in the new multi-frequency ECRH system at the ASDEX Upgrade tokamak experiment. It works at 105 GHz and 140GHz with output power 610kW and 820kW respectively at a pulse length of 10s. A further extension of the system with 3 more gyrotrons is underway. These gyrotrons will be step-tunable...
The power deposition in the plasma is primarily determined by the magnetic field B(r). For a single frequency ECRH system this has the consequence that for central heating the magnetic field is no longer a free parameter. However, for plasmas with different plasma currents or different equilibria, the magnetic field should be a free parameter in order to operate at a reasonable edge safety factor...
The first two-frequency GYCOM gyrotron Odissey-1 has been installed and put into operation in the new multi-frequency ECRH system at the ASDEX Upgrade tokamak experiment.
Summary form only given. The power deposition in ECRH (electron cyclotron resonance heating) of fusion plasmas is primarily determined by the magnetic field. For a single frequency ECRH system this has the consequence that for central heating the magnetic field is no longer a free parameter. However, for tokamak plasmas with different plasma currents or different equilibria, the magnetic field should...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.