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Browsing 02.National Laboratory Astana by Author "Norem, J."

Browsing 02.National Laboratory Astana by Author "Norem, J."

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  • Advanced Surface Polishing For Accelerator Technology Using Ion Beams 
    Insepov, Z.; Norem, J.; Hassanein, A.; Wu, A. T. (American Institute of Physics, 2009-03)
    Surface erosion problems are common in the development of TeV accelerators, fusion and fission reactors, semiconductor, optical and magnetic storage devices, and Extreme Ultra-Violet (EUV) lithography devices. We have ...
  • A General Model of Vacuum Arcs in Linacs 
    Norem, J.; Insepov, Z. (Proceedings of NAPAC2016, Chicago, IL, USA, 2017-01)
    We are developing a general model of breakdown and gradient limits that applies to accelerators, along with other high field applications such as power grids and laser ablation. We have considered connections with failure ...
  • A model of rf breakdown arcs 
    Insepov, Z.; Bross, A.; Qian, Z.; Norem, J.; Huang, D.; Veitzer, S.; Torun, Y. (Fermilab, 2008)
    This paper presents a rst iteration of a model that attempts to describe all aspects of breakdown in rf cavities and provides some estimates of the parameters and parameter ranges involved, as an aid to producing more ...
  • Breakdown in RF cavities 
    Norem, J.; Hassanein, A.; Insepov, Z.; Konkashbaev, I. (Proceedings of 2005 Particle Accelerator Conference, Knoxville, Tennessee, 2005)
    We present a simple model of breakdown in rf cavities. For most events this involves tensile stress and tensile strength, however other effects can also contribute. We discuss the effects of different materials, fatigue, ...
  • Can surface cracks and unipolar arcs explain breakdown and gradient limits? 
    Insepov, Z.; Norem, J. (J. Vac. Sci. Technol, 2013)
    We argue that the physics of unipolar arcs and surface cracks can help understand rf breakdown, and vacuum arc data. We outline a model of the basic mechanisms involved in breakdown and explore how the physics of unipolar ...
  • Computational problems in modeling arcs 
    Norem, J.; Insepov, Z. (American Institute of Physics, 2016-10)
    We explore the reasons why there seems to be no common model for vacuum arcs, in spite of the importance of the field and the level of effort expended over more than one hundred years.
  • Effects of surface damage on rf cavity operation 
    Hassanein, A.; Insepov, Z.; Norem, J.; Moretti, A.; Qian, Z.; Bross, A.; Seidman, D. N. (Physical Review Special Topics-Accelerators and Beams, 2006)
    We describe a model of damage in rf cavities and show how this damage can limit cavity operation. We first present a review of mechanisms that may or may not affect the ultimate fields that can be obtained in rf cavities, ...
  • High Surface Fields in Superconducting rf Cavities. In Proceedings of SRF 
    Norem, J.; Insepov, Z.; Bauer, P.; Seidman, D.N.; Sebastian, J.; Yoon, K. (Proceedings of the 12th International Workshop on RF Superconductivity, Cornell University, 2005)
    Field emission in cavities requires electric fields that can be high enough to damage materials. We outline a model of breakdown and field emission from local asperities, and show how electric field effects, and field ...
  • AN INTEGRATED APPROACH TO UNDERSTANDING RF VACUUM ARCS 
    Norem, J.; Insepov, Z.; Hassanein, A. (Nature Research, 2021-01-27)
    Although used in the design and costing of large projects such as linear colliders and fusion tokamaks, the theory of vacuum arcs and gradient limits is not well understood. Almost 120 years after the isolation of vacuum ...
  • Ion Solid Interaction And Surface Modification At RF Breakdown In High‐Gradient Linacs 
    Insepov, Z.; Norem, J.; Veitzer, S. (American Institute of Physics, 2011-06)
    Ion solid interactions have been shown to be an important new mechanism of unipolar arc formation in high-gradient rf linear accelerators through surface self-sputtering by plasma ions, in addition to an intense surface ...
  • Modeling arcs 
    Insepov, Z.; Norem, J.; Vetizer, S.; Mahalingam, S. (American Institute of Physics, 2011-12)
    Although vacuum arcs were first identified over 110 years ago, they are not yet well understood. We have since developed a model of breakdown and gradient limits that tries to explain, in a self-consistent way: arc triggering, ...
  • Modeling of High-Gradient Vacuum Breakdown 
    Ainabayev, A.; Berdenova, B.; Norem, J.; Insepov, Z. (arXiv preprint arXiv:1410.6501, 2014)
    Comsol finite element technique was applied to study heating and cooling of a microspot on the cathode surface. The reasons why there seems to be no common model for vacuum arcs, in spite of the importance of this field ...
  • Modeling RF breakdown arcs 
    Insepov, Z.; Norem, J.; Proslier, T.; Huang, D.; Mahalingam, S.; Veitzer, S. (arXiv preprint arXiv:1003.1736, 2010)
    We describe breakdown in 805 MHz rf accelerator cavities in terms of a number of self-consistent mechanisms. We divide the breakdown process into three stages: (1) we model surface failure using molecular dynamics of ...
  • Modeling Vacuum Arcs 
    Insepov, Z.; Norem, J.; Proslier, T.; Huang, D.; Mahalingam, S.; Veitzer, S. (arXiv preprint arXiv:1006.3770, 2010)
  • Modeling vacuum arcs in linac structures 
    Norem, J.; Moretti, A.; Insepov, Z.; Nurkenov, S. (Proceedings of PAC2013, Pasadena, 2013)
    We describe our vacuum arc model, which divides breakdown into four stages: trigger, plasma formation, plasma evolution and surface damage. We have modeled all four stages numerically and find that the properties of surface ...
  • Sheath parameters for non-Debye plasmas: Simulations and arc damage 
    Morozov, I. V.; Norman, G. E.; Insepov, Z.; Norem, J. (Physical Review Special Topics-Accelerators and Beams, 2012)
    This paper describes the surface environment of the dense plasma arcs that damage rf accelerators, tokamaks, and other high gradient structures. We simulate the dense, nonideal plasma sheath near a metallic surface using ...
  • Simulations of Fast X-Ray Detectors Based on Multichannel Plates 
    Adams, B.; Insepov, Z.; Ivanov, V.; Norem, J. (Proceedings of IPAC2012, New Orleans, Louisiana, 2012)
    High-performance detectors with high spatial and time resolutions are required in applications such as imaging of fast processes, time-resolved coherent scattering, and time-resolved X-ray spectroscopy. Recently a new type ...
  • The Interactions of Surface Damage on RF Cavity Operation 
    Norem, J.; Bross, A.; Hassanein, A.; Qian, Z.; Yoon, K. E.; Moretti, A.; Li, D. (Fermilab, 2006-06)
    Studies of low frequency RF systems for muon cooling has led to a variety of new techniques for looking at dark currents, a new model of breakdown, and, ultimately, a model of RF cavity operation based on surface damage. ...
  • The problem of RF gradient limits 
    Norem, J.; Insepov, Z.; Huang, D.; Mahalingam, S.; Veitzer, S. (American Institute of Physics, 2010-03)
    We describe breakdown in rf accelerator cavities in terms of a number of mechanisms. We divide the breakdown process into three stages: 1) we model surface failure using molecular dynamics of fracture caused by electrostatic ...
  • Vacuum arcs and gradient limits 
    Norem, J.; Moretti, A.; Insepov, Z. (Proceedings of 2011 Particle Accelerator Conference, New York, 2011)
    We have been extending and refining our model of vacuum breakdown and gradient limits and describe recent developments. The model considers a large number of mechanisms, but finds that vacuum arcs can be described fairly ...