Magnetic priming effects on noise, startup, and mode competition in magnetrons

Magnetic Priming of a Relativistic Magnetron

“…Enhancements to the radial and θ directed components of the magnetic field were not expected to be of great concern in cases where the magnetic priming structures are of approximately the same size as the magnetron interaction region, such as in the work done by Neculaes et al [10][11][12][13]19] and Luginsland et al [21], or in cases where they were ignored completely, as with the 2-D simulations performed by Jones et al [16][17][18]. Because the magnetic priming wire lengths proposed for use in the relativistic magnetron can be as small as 15% of the anode length, these edge effects are more important.…”

“…Thus, traditional strapping methods cannot be used in relativistic magnetrons [48]. Another technique used to increase mode control, as well as enhance other aspects of magnetron performance such as reducing the time to start oscillation, is magnetic priming [10][11][12][13][14][15]. This technique introduces systematic azimuthal variations in the axial magnetic field of the magnetron.…”

“…The aspects of magnetron performance in which improvement is sought include mode control, peak power, start-oscillation time, and pulse length. One promising technique that has emerged as a way to enhance magnetron performance is "magnetic priming" [10][11][12][13][14][15][16][17][18][19].…”

“…In order to create the azimuthal magnetic field variations in the previous oven magnetron experiments, small rare-earth magnets were placed on the outside of the annular, permanent magnets that are standard on the devices [10][11][12][13]19], as shown in Figure 1 During the course of the magnetic priming experiments on the UM/L-3 relativistic magnetron, it was discovered that window flashover was occurring on the vacuum side of the microwave windows [37]. This window flashover was limiting the microwave power and pulse width that could be extracted from the magnetron.…”

Relativistic magnetron operation with explosive emission and ferroelectric plasma source cathodes

“…The basic physical phenomena which are govern relativistic magnetron operation are well described in textbooks and reviews [1][2][3] and several methods for improving it operation, i.e., fast turn on of MW generation [4], elimination of mode competition [5], improved extraction of the MW [6], and improvements in electron emission [7,8], have been suggested. However, the influence of the cathode plasma on the beginning, duration and other parameters of the MW generation is not yet completely understood.…”