Linear Theory of Instabilities Generated by an Electron Beam in a Metamaterial-Loaded Waveguide

Dataset · Thu Feb 21 04:00:00 EST 2019

DOI:https://doi.org/10.7910/DVN/MBSWTT· OSTI ID:1881279

Lu, Xueying ^[1]; Shapiro, Michael A.; Temkin, Richard J.

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1. OSTI

We present the linear theory of the starting current of Cherenkov-cyclotron and Cherenkov instabilities generated by an electron beam passing through a metamaterial-loaded waveguide. Effective medium theory is used to represent the metamaterial structure properties. The theory predicts that the instabilities compete, with the Cherenkov-cyclotron mode dominating at lower magnetic field and the Cherenkov instability at higher magnetic field. The theoretical results are compared to results from recent experiments at MIT using a 490 kV, 84 A electron beam in magnetic fields of 300 G to 1500 G. For an effective medium model fitted to the MIT experimental parameters, theory predicts that the Cherenkov-cyclotron mode will dominate below 780 G and the Cherenkov mode above 780 G, in good agreement with experimental observations of switching between these modes at 750 G. The analytical theory allows a better understanding of the mode competition and the dependence of the instabilities on key parameters such as voltage, current and magnetic field.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• DOE Contract Number: SC0015566
• OSTI ID: 1881279
• Country of Publication: United States
• Language: English