Magnétron

Résumé

vignette|Magnétron dans son boîtier. Un magnétron est un dispositif qui transforme l'énergie cinétique des électrons en énergie électromagnétique, sous forme de micro-onde. Il s'agit d'un tube à vide sans grille où les électrons émis par une cathode se dirigent vers une anode mais sont déviés par un champ magnétique en une trajectoire en spirale. L'interaction entre le faisceau d'électrons et l'anode produit l'onde électromagnétique. Initialement, l'anode était fendue en plusieurs segments mais dans les années 1940, c'est le type à cavités résonnantes, plus performant, qui s'est imposé. Le développement du magnétron a été crucial dans celui du radar et donc dans le déroulement de la Seconde Guerre mondiale. Depuis, il s'est répandu dans d'autres domaines, notamment l'électroménager avec le four à micro-ondes. Histoire vignette|gauche|Magnétron à anode à segments multiples, antérieur au magnétron à cavité :1) cathode, 2) anodes, 3) aimants permanents. vignette|gauche|

Source officielle

https://fr.wikipedia.org/wiki/Magn%C3%A9tron

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Publications associées (36)

Publications associées

Chargement

Personnes associées (2)

Personnes associées

Chargement

Unités associées (2)

Unités associées

Chargement

Concepts associés (47)

Concepts associés

Chargement

Cours associés (4)

Micro- and nanofabrication can be taught to students and professionals by textbooks and ex-cathedra lectures, but the real learning comes from seeing the manufacturing steps as they happen. This MOOC will not only explain the basics of microfabrication but also show the practice through videos.

The course covers the fundaments of bioelectronics and integrated microelectronics for biomedical and implantable systems. Issues and trade-offs at the circuit and systems levels of invasive microelectronic systems as well as their eluding designs, methods and classical implementations are discussed

This course gives an introduction to production methods and manufacturing technologies used in microengineering. The focus is given on the understanding of physical phenomena underlying the processes, the relation between materials, manufacturing processes and design, as well as economical aspects.

Afficher plus

Cours associés

Chargement

Séances de cours associées (5)

Séances de cours associées

Chargement

Diamond optomechanical crystals in the resolved-sideband regime

Michael J. Burek

We demonstrate diamond optomechanical crystals (OMCs), which support a similar to 6 GHz mechanical cavity coupled to a co-resonant similar to 200 THz photon field. Diamond OMCs are optically driven to a cooperativity >1, highlighted by observed 'phonon lasing'.

Ieee2016

Chargement

Beam-cavity interactions in high power cyclotrons

Lukas Stingelin

The ring cyclotron of the Paul Scherrer Institute (PSI) accelerates an intense proton beam from 72MeV up to 590MeV. This happens in four cavities of very high quality factor, oscillating in the fundamental mode. The beam can excite parasitic oscillation modes (HOMs), because of its time structure. Measurements showed that their field can leak out into the vacuum chamber. Until now, there is no tool available to predict the potentially harmful effect of these HOMs onto the beam operation of the cyclotron. It is foreseeable that these effects might play a role if even higher beam currents have to be accelerated. This dissertation therefore deals with the numerical analysis and measurement of beam-cavity interactions. First calculations for a single cavity, interacting with a proton bunch were performed with MAFIA's eigenmode- (E3), time domain- (T3) and particle-in-cell (TS3) solvers. However, the structured grid and the limited computing performance of MAFIA make realistic simulations impossible. A simplified computation method is developed in this dissertation since a self-consistent simulation is impossible on today's computers: The parallel eigensolver Omega3P of the Stanford Linear Accelerator Center (SLAC) allowed us to calculate eigenmodes of the entire ring cyclotron for the first time ever. The rf fields are expanded onto a superposition of these modes and the excitation is calculated in frequency domain. Trajectories of the particles in the static magnetic field, superposed with the space charge fields and the beam excited HOMs, are then simulated. However, the quantitative accuracy of this model is still limited. On the one hand, because of the simplification in the geometry of the simulated rf structure, which otherwise would lead to a problem size going beyond the available computing resources. On the other hand, because it is not yet possible to simulate strongly absorbing boundaries more accurately. The simulation results confirm that up to proton beam currents of 2mA, corresponding to the routinely accelerated beam intensities, only a small deformation of the charge distribution appears. This thesis leads to a new simulation tool for further studies of intensity increases in high power cyclotrons.

EPFL2004

Chargement

From pulsed-DCMS and HiPIMS to microwave plasma-assisted sputtering: Their influence on the properties of diamond-like carbon films

David Brown, Caroline Hain, Aïcha Hessler-Wyser, Johann Michler, Thomas Nelis

The fabrication of high-hardness non-hydrogenated diamond-like carbon (DLC) via standard magnetron sputtering (MS) is often hindered by the low sputtering yields and ionisation rates of carbon, therefore investigations into pulsed alternatives of MS, else sputtered species post-ionisation methods, are of particular interest. This work focuses on investigating the influence of pulsed-direct current MS (pDCMS), high power impulse magnetron sputtering (HiPIMS) and their microwave plasma-assisted (MA-pDCMS, MA-HiPIMS) variants on the properties of the fabricated DLC films. Two setups were used for the pDCMS-and HiPIMS-based methods, respectively. The films were characterised using Raman spectroscopy, nanoindentation, X-ray reflectometry and scanning electron microscopy, where the pDCMS-produced films were additionally characterised by film-stress measurements. Moreover, in situ time-resolved Langmuir probe plasma analysis was performed under HiPIMS and MA-HiPIMS conditions to analyse the influence of the magnetron and microwave plasmas on one another. For both DCMSand HiPIMS-based procedures, it was found that the addition of microwave plasma did not facilitate attaining hardnesses beyond 30 GPa, however, it did enable modifying the morphology of the films. Furthermore, this study shows the potential of synchronised sputtering with substrate biasing, as well as the importance of microwave plasma source positioning in relation to the substrate.

ELSEVIER SCIENCE SA2022

Chargement

Beam-cavity interactions in high power cyclotrons

Lukas Stingelin

EPFL2004