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Leioa, Spain

Jugo J.,University of the Basque Country | Eguiraun M.,ESS Bilbao
Proceedings of the IEEE International Conference on Control Applications

Event-based control (EBC) is growing in importance since this paradigm leads to a better integration with networked systems. Particularly due to the distributed and asynchronous inherent nature of such systems. The reported main advantage is the reduction of the control rate allowing a less saturated communication network. This fact has been proved with different EBC schemes, as using impulse control schemes within stochastic environments and different PID structures. In this work, the experimental study of an event based input-output control scheme is presented, following the sporadic control approach and implemented in a networked environment. In this scenario, noise minimizes the advantages of event-based schemes. The use of a filtering strategy minimizes its effect, restoring the reduction of the control rate. This kind of approach leads to interesting practical applications. Simulation and experimental results show the performance of the control approach under study. © 2010 IEEE. Source

Cortazar O.D.,University of Castilla - La Mancha | Megia-Macias A.,ESS Bilbao | Vizcaino-De-Julian A.,ESS Bilbao | Tarvainen O.,University of Jyvaskyla | And 2 more authors.
Review of Scientific Instruments

First results from an ultra-fast frame image acquisition diagnostic coupled to a 2.45 GHz microwave hydrogen discharge are presented. The plasma reactor has been modified to include a transparent doubled shielded quartz window allowing to viewing the full plasma volume. Pictures describing the breakdown process at 1 μs exposure time have been obtained for integrated visible light signal, Balmer-alpha, Balmer-beta lines, and Fulcher-band. Several different plasma emission distributions are reported. The distribution depends on the magnetic field configuration, incident microwave power, and neutral gas pressure. © 2013 AIP Publishing LLC. Source

Cortazar O.D.,University of Castilla - La Mancha | Megia-Macias A.,ESS Bilbao | Vizcaino-De-Julian A.,ESS Bilbao
Review of Scientific Instruments

An experimental study of temperature and density evolution during breakdown in off-resonance ECR hydrogen plasma is presented. Under square 2.45 GHz microwave excitation pulses with a frequency of 50 Hz and relative high microwave power, unexpected transient temperature peaks that reach 18 eV during 20 μs are reported at very beginning of plasma breakdown. Decays of such peaks reach final stable temperatures of 5 eV at flat top microwave excitation pulse. Evidence of interplay between incoming power and duty cycle giving different kind of plasma parameters evolutions engaged to microwave coupling times is observed. Under relative high power conditions where short microwave coupling times are recorded, high temperature peaks are measured. However, for lower incoming powers and longer coupling times, temperature evolves gradually to a higher final temperature without peaking. On the other hand, the early instant where temperature peaks are observed also suggest a possible connection with preglow processes during breakdown in ECRIS plasmas. © 2012 American Institute of Physics. Source

Some parts of austenitic stainless steels structures which must operate with radiofrequency in ultra high vacuum need to be machined with very high precision and need to have a copper plating treatment. The heat treatment for stress relief due to machining proposed by the major research centres is performed by vacuum furnaces, that do not damage the structure of the material, but these ovens are very complex and unusual, especially for large pieces. To facilitate this process and reduce its cost is proposed to realize in common furnaces of inert atmosphere. But it is necessary to perform the tests of intergranular corrosion susceptibility and adhesion of copper, to validate the change of the process. Source

Kaftoosian A.,ESS Bilbao | Gonzalez P.J.,ESS Bilbao
IPAC 2014: Proceedings of the 5th International Particle Accelerator Conference

Design and development of a 30 kW, 352 MHz pulsed RF solid-state power amplifier to be utilized for feeding re-bunching cavities in proton linac, is in progress at ESSBilbao. This modular transmitter is based on in-phase combination of compact, water-cooled 2 kW RF power modules, each one consists of two combined LDMOS transistors in balanced configuration. The modules include individual bias control, measurement and supply circuits. Gate modulation is foreseen to increase efficiency in pulsed regime that is up to 3ms RF pulse width and 10% duty cycle. The 2 kW RF power module has been developed and the test results are discussed. Copyright © 2014 CC-BY-3.0 and by the respective authors. Source

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