Sökning: "accelerators"

Visar resultat 21 - 25 av 93 avhandlingar innehållade ordet accelerators.

  1. 21. Low Secondary Electron Yield Carbon Coatings for Electron Cloud Mitigation in Modern Particle Accelerators

    Författare :Christina Yin Vallgren; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Raman spectroscopy; NRA; amorphous carbon; secondary electron yield; LIU; X-Ray Photoelectron Spectroscopy; SEY; AFM; electron cloud; SPS dipole magnet;

    Sammanfattning : In order to upgrade the Large Hadron Collider (LHC) performance to be oriented towards higher energies and higher intensities in the future, a series of improvementsof the existing LHC injectors is planned to take place over the next few years. Electron cloud effects are expected to be enhanced and play a central role in limiting theperformance of the machines of the CERN complex. LÄS MER

  3. 22. Studies of Heavy Ion Induced Desorption in the Energy Range 5-100 MeV/u

    Författare :Emma Hedlund; Lars Westerberg; Oleg Malyshev; Manfred Leisch; Uppsala universitet; []
    Nyckelord :Physics; Heavy Ion Induced Desorption; Ultra High Vacuum; NEG Coating; Heavy Ion Accelerators; Test Particle Monte-Carlo; Gas Flow; Throughput; Laser Refractometry; Metrology; Fysik;

    Sammanfattning : During operation of heavy ion accelerators a significant pressure rise has been observed when the intensity of the high energy beam was increased. The cause for this pressure rise is ion induced desorption, which is the result when beam ions collide with residual gas molecules in the accelerator, whereby they undergo charge exchange. LÄS MER

  4. 23. Performance Characterization and Optimization of In-Memory Data Analytics on a Scale-up Server

    Författare :Ahsan Javed Awan; Eduard Ayguade; Mats Brorsson; Vladimir Vlassov; Lieven Eeckhout; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Workload Characterization; Big Data Analytics; Multicore Performance; Apache Spark; Near Data Processing; NUMA; Hyperthreading; Prefetchers; Coherently attached accelerators; Informations- och kommunikationsteknik; Information and Communication Technology;

    Sammanfattning : The sheer increase in the volume of data over the last decade has triggered research in cluster computing frameworks that enable web enterprises to extract big insights from big data. While Apache Spark defines the state of the art in big data analytics platforms for (i) exploiting data-flow and in-memory computing and (ii) for exhibiting superior scale-out performance on the commodity machines, little effort has been devoted to understanding the performance of in-memory data analytics with Spark on modern scale-up servers. LÄS MER

  5. 24. On integrity assessment of IGBT-based power stacks used in magnet power supplies for particle accelerators

    Författare :Panagiotis Asimakopoulos; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : This thesis analyses an electrical testing method for assessing the integrity of an IGBT-based power stack assembly during factory acceptance tests and service stops. The method combines vce measurements with high current in the Zero Temperature Coefficient (ZTC) operating region and with low sensing current within a specific current cycle using a proposed sampling and filtering technique. LÄS MER

  7. 25. Extreme Electron Beams and Brilliant X-rays : Generation, Manipulation and Characterization of Relativistic Electron Beams for and from Plasma-Based Accelerators

    Författare :Jonas Björklund Svensson; Atomfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; laser; plasma; wakefield; acceleration; accelerator; relativistic; electrons; x-rays; ultra-fast; betatron; laser-wakefield acceleration; plasma-wakefield acceleration; Fysicumarkivet A:2020:Björklund;

    Sammanfattning : This thesis is based on work done by the author on the development of plasma-based electron accelerators driven by ultra-intense laser pulses and dense electron bunches. Plasma based accelerators have several benefits, such as accelerating fields around 1000 times stronger than in “conventional” radio-frequency accelerators, which can allow for shrinking the overall footprint of the accelerator. LÄS MER