Progress towards a gap free dielectric-loaded accelerator

Jing, C.; Kanareykin, A.; Konecny, R.; Power, John; Gold, Steven H.; Kazakov, S.

doi:10.1109/pac.2007.4440698

Cited by 8 publications

(3 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to the preceding studies of DLA structures, a dielectric joint breakdown occurred at microgaps [27] and rf power absorption caused by single-surface multipactor was experimentally found [28,29]. Therefore, in order to realize a high-gradient DAA structure, it is essential to develop a careful design of input coupler and dielectric cell assembly to avoid the rf breakdown and to mitigate multipactoring.…”

Section: Discussionmentioning

confidence: 99%

Dielectric assist accelerating structure

Satoh

Yoshida

Hayashizaki

2016

Phys. Rev. Accel. Beams

View full text Add to dashboard Cite

A higher-order TM 02n mode accelerating structure is proposed based on a novel concept of dielectric loaded rf cavities. This accelerating structure consists of ultralow-loss dielectric cylinders and disks with irises which are periodically arranged in a metallic enclosure. Unlike conventional dielectric loaded accelerating structures, most of the rf power is stored in the vacuum space near the beam axis, leading to a significant reduction of the wall loss, much lower than that of conventional normal-conducting linac structures. This allows us to realize an extremely high quality factor and a very high shunt impedance at room temperature. A simulation of a 5 cell prototype design with an existing alumina ceramic indicates an unloaded quality factor of the accelerating mode over 120 000 and a shunt impedance exceeding 650 MΩ=m at room temperature.

show abstract

Section: Discussionmentioning

confidence: 99%

Dielectric assist accelerating structure

Satoh

Yoshida

Hayashizaki

2016

Phys. Rev. Accel. Beams

View full text Add to dashboard Cite

show abstract

“…It is revealed in [16,17] that integration of the dielectric parts of the coupler and tube can prevent the RF breakdown occurred because of the air gap that existed at the joint of the coupler and dielectric tube. Additionally, in [17,18] gap-free structures are introduced to eliminate this problem. Choosing dielectric materials with high permittivity, very low loss tangent, and low secondary electron emission coefficient (SEEC) has made significant progress in decreasing the dielectric loss and multipactoring [17].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of transmission line model to analyze the matching section of a dielectric-loaded accelerator with sharp discontinuities

Joozdani

2022

J. Inst.

View full text Add to dashboard Cite

In this paper, a compact and single-mode X-band dielectric-loaded matching section with constant tilt angle, blended edges, and two discontinuities at both ends is analyzed by the transmission line model. This matching section is designed as a high-power injection coupler to a dielectric-loaded accelerating structure (DLA). Although the transmission line model is a powerful tool for single-mode structures, because of radial inhomogeneity and lack of single value for characteristic impedance in dielectric-loaded structures, this method is not applicable in non-uniform dielectric-loaded structures. To solve this problem, it is shown that a dielectric-loaded waveguide (DLW) can be modeled by a dielectric-filled waveguide (DFW) with the same parameters of the phase constant, power flow, and dielectric loss. The characteristic impedance of a dielectric-filled waveguide can be determined by three structural parameters of the real and imaginary parts of the dielectric material and inner radius. These structural parameters can be found by solving a non-linear equation system made by equality of the parameters of the dielectric-loaded and dielectric-filled waveguides. To analyze the matching section, it is stratified to low thickness and uniform DLWs in the propagation direction and every segment is substituted by its equal DFW model. However, because of sharp variation in dielectric region at two ends of the flared section, solving the non-linear equation system is difficult at these points due to the lack of a proper initial point for the answer. Therefore, two virtual sections are added at the discontinuities to smoothen the variation of the dielectric region. Then, the total transmission matrix and scattering matrix parameters can be obtained without considering the added virtual sections. Moreover, the matching section is simulated by a full-wave electromagnetic software and the results of the scattering matrix parameters are compared with the ones of the proposed method. It is shown that there is a good agreement between the total behavior of the simulation and analytical results and the proposed method has acceptable accuracy.

show abstract

“…It is shown that using materials with low secondary electron emission for the fabrication of the dielectric part or coating the inner surface of the tube can significantly reduce the multipactor loading. Also, gap-free structures are introduced to eliminate the gap between the dielectric parts of the tube and coupler at the joints known as a source of breakdown and multipactor occurrence [15][16][17]. Recently, it has been demonstrated that applying a powerful external magnetic field in the axial direction of a DLA can completely suppress the effect of multipactoring [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Approximate method for electromagnetic analysis of a dielectric-loaded coupler used in accelerating structures

Joozdani¹

2020

J. Inst.

View full text Add to dashboard Cite

In this paper, a theoretical analysis of a dielectric-loaded coupler based on the transmission line model is proposed. One of the major challenges in the design of dielectric-loaded accelerating (DLA) structures is the proper coupling of high-power RF into the dielectric-loaded tube. The considered X-band coupler consists of a tapered dielectric-loaded tube converting TM 01 mode in a conventional circular waveguide to the one in a uniform dielectric-loaded tube. To analyze the coupler with an approximation based on the transmission line model, the coupler is divided into a large number of sections in the propagation direction. Every section is considered as a short-length uniform transmission line with its own characteristic impedance and propagation constant. Then, scattering matrix parameters of the coupler are calculated by the total transmission matrix of the structure. To investigate the accuracy of the proposed method, two coupler prototypes with different dielectric materials are considered and their scattering matrix parameters are obtained by the proposed method and full-wave simulation. Overall, it is shown that the analytical results are sufficiently close to the simulation and optimizations performed by the proposed method can be used as the starting point for full-wave or numerical optimization.

show abstract

Progress towards a gap free dielectric-loaded accelerator

Cited by 8 publications

References 1 publication

Dielectric assist accelerating structure

Dielectric assist accelerating structure

Enhancement of transmission line model to analyze the matching section of a dielectric-loaded accelerator with sharp discontinuities

Approximate method for electromagnetic analysis of a dielectric-loaded coupler used in accelerating structures

Contact Info

Product

Resources

About