Abstract
The disk-beam relativistic klystron oscillator (DB-RKO) with the radial-line high frequency structure is one of the attractive high power microwave (HPM) sources due to its specific virtues of weak space-charge effect, high power handling capacity and strong electron collection ability. However, such a device generally exhibits a bulky volume in the radial direction, retarding its actual applications in some compact occasions. Besides, it usually saturates slowly because of the insufficient beam-wave coupling strength. For this purpose, a compact DB-RKO with a rapid saturation process is proposed and physically designed in this paper. By compressing the axial width of the electron beam drift tube suitably, the beam-wave coupling strength is enhanced clearly and the saturation process is accelerated significantly. The whole beam-wave interaction structure is shortened with a radial length of about 5 cm. Besides, in order to increase the device compactness further, an improved magnetic-excited method is presented to enhance the magnetic field in the diode area by introducing a pair of soft-magnets. Furthermore, with the guiding of a low magnetic field of 0.4 T, the compact DB-RKO is experimentally demonstrated to be capable of generating Ku-band HPM radiations with a peak power of 810 MW, a power conversion efficiency of 28%, a center frequency of 14.19 GHz and a pulse duration of about 27 ns. The proposed DB-RKO is promising for the package of the permanent magnets which are preliminarily designed in this paper.
Highlights
High power microwave (HPM) technology has been extensively investigated during the past decades owing to its many potential applications in the civil and military fields [1], [2]
By improving the electron beam quality and the high frequency interaction structure, we have preliminarily demonstrated the feasibility of this technical scheme with a disk-beam relativistic klystron oscillator (DB-RKO) which was capable of generating Ku-band gigawatt-level microwave radiations in the experiment [21]
EXPERIMENTAL RESULTS The compact Ku-band DB-RKO is operated on a SINUS-type electron beam accelerator with a full width at half maximum (FWHM) pulse duration of about 55 ns
Summary
High power microwave (HPM) technology has been extensively investigated during the past decades owing to its many potential applications in the civil and military fields [1], [2]. Among the multifarious HPM sources, the radial-line microwave devices driven by the disk-shape IREBs are attractive due to their specific merits of weak space-charge effect, high power handling capacity and strong electron collection ability [15]–[17]. In such kind of device, the electron beam is emitted and propagates along. The resonant cavities are arranged radially and the radio-frequency (RF) field density can be balanced across the output gaps where the RF breakdown occurs. This type of devices is expected to produce microwave radiations in high frequencybands with high power, high efficiency, low guiding magnetic field and compact size
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