Asymmetric modes suppression in Cerenkov device using anisotropic media

Abstract

Asymmetric modes competition in Cerenkov devices were studied with a view to developing a novel method to suppress modes competition, based on loading of the slow-wave structure (SWS) with an anisotropic medium. Due to differences in the field distribution between the asymmetric and symmetric modes, the asymmetric modes are susceptible to significant attenuation in anisotropic media with an appropriate imaginary part for the azimuthal permittivity. In contrast, the symmetric modes, such as the TM01 mode, incur no such losses. Using the EH11 mode as an example, the quality factor obtained from experiments involving the SWS loaded with an anisotropic medium was reduced by approximately 90% compared with that for a copper SWS. The attenuation was sufficiently high that the electromagnetic fields for the asymmetric modes were barely established, indicating that the suppression technique was highly effective. The approach provides a feasible way to eliminate asymmetric modes in high-power microwave (HPM) sources and may lead to a range of new applications in HPM systems.

Investigation and suppression of asymmetric modes competition in Cerenkov device by conductivity anisotropic material loading

“…A potential approach to suppress the asymmetric mode was proposed and a preliminary experiment carried out in 2019 [23]. In this paper, we present theoretical and numerical investigations of the asymmetric mode competition in a Kuband Cerenkov generator.…”

Advancing electromagnetic field modeling in axially anisotropic media with conformal method in 3D cylindrical coordinate systems

“…The RBWO is becoming an international research hotspot in the field of high-power microwave due to its high power, high efficiency and simple structure. Some scholars have used anisotropic media with azimuthal conductivity to suppress the asymmetric mode competition in Cerenkov devices [20,21], making the method proposed in this paper a valuable tool for such devices. Applying this method to PIC simulation, the X-band RBWO shown in figure 9 is selected as the simulation object, figure 9(a) is the case where the anisotropic medium is not filled, and figure 9(b) is the case where the anisotropic medium is filled on the axis.…”

“…However, the overmoded structures can lead to asymmetric mode competition in the device, which can severely reduce the output power and affect the normal operation of the device [14][15][16][17][18][19]. To address this issue, some scholars have proposed a simple and efficient method, which involves filling an anisotropic medium with azimuthal conductivity in the Cerenkov device, effectively suppressing the asymmetric mode competition [20,21]. This method has the advantage of not affecting the working mode of the device and has shown promising results in previous studies [20,21].…”

“…To address this issue, some scholars have proposed a simple and efficient method, which involves filling an anisotropic medium with azimuthal conductivity in the Cerenkov device, effectively suppressing the asymmetric mode competition [20,21]. This method has the advantage of not affecting the working mode of the device and has shown promising results in previous studies [20,21]. At present, the PIC method is frequently employed to simulate high-power microwave devices [22][23][24][25], but there is a lack of literature specifically studying the conformal method in PIC simulation when filling such media in 3D cylindrical coordinate systems, which presents a significant gap in the current research on high-power microwave devices and highlights the need for further studies in this area.…”

“…To demonstrate the applicability of this method to the numerical simulation of high-power microwave devices, it is applied to a 3D cylindrical coordinate system PIC simulation, using an X-band RBWO as the simulation object. Previous studies have shown that the use of an azimuthal conductivity can effectively suppress asymmetric mode competition in the device [20,21]. Therefore, an anisotropic medium with a thickness of 4 mm is filled along the axis of the RBWO.…”