Design Of RF Window Research Articles

Broadband high power rf window design for the BNL Electron Ion Collider

Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility are collaborating on the design and construction of the next Electron Ion Collider (EIC) to be built at BNL. The EIC is a unique high-energy, high-luminosity, polarized electron-proton/ion collider. The EIC accelerator complex needs about 10 new rf and SRF systems with frequencies spanning 24 MHz to 1773 MHz, requiring more than 60 new high-power fundamental power couplers (FPCs). These couplers will operate in either pulsed mode or continuous wave mode with peak traveling wave power ranging from 10 s to 380 kW. Here we present our design for a 1-MW broadband rf window suitable for EIC rf and SRF systems with operating frequencies up to 591 MHz. This design takes advantage of the numerous synergies between the various rf and SRF systems to make it broadly applicable. The rf window design criteria are based on the requirement for the 591-MHz electron storage ring (ESR) SRF cavities, as it will operate at both the highest traveling wave power and the highest peak power over the EIC $\mathrm{rf}/\mathrm{SRF}$ complex. The results presented will detail the FPC power requirement, rf window choices, design criteria, and multiphysics performance in the most critical application, the ESR SRF cavity, and how the rf window design applies to other EIC $\mathrm{rf}/\mathrm{SRF}$ systems.

Octree-based voxel model for representation of spatial conflicts detected using domain mapping matrix across multiple design domains

This paper discusses use of domain mapping matrix (DMM) to detect spatial conflicts across multiple design domains and use of octree-based voxel model for representation of these spatial conflicts. A framework has been developed to create octree-based voxel model linked with intended empty spaces in product, which are associated with design requirements, product lifecycle states and with connected design domains. Knowledge in system modelling language (SysML), is used to select criteria for building octree voxel model. Two case studies of coupled cavity travelling wave tube (CCTWT) slow wave structure (SWS) design and high power RF window design, have been taken to showcase the code capabilities. Octree voxels inside CAD platform, show and represent spatial conflicts, detected by associativity modelling of empty space blocks inside CAD along with the product knowledge in SysML model.

Octree-based voxel model for representation of spatial conflicts detected using domain mapping matrix across multiple design domains

This paper discusses use of domain mapping matrix (DMM) to detect spatial conflicts across multiple design domains and use of octree-based voxel model for representation of these spatial conflicts. A framework has been developed to create octree-based voxel model linked with intended empty spaces in product, which are associated with design requirements, product lifecycle states and with connected design domains. Knowledge in system modelling language (SysML), is used to select criteria for building octree voxel model. Two case studies of coupled cavity travelling wave tube (CCTWT) slow wave structure (SWS) design and high power RF window design, have been taken to showcase the code capabilities. Octree voxels inside CAD platform, show and represent spatial conflicts, detected by associativity modelling of empty space blocks inside CAD along with the product knowledge in SysML model.

Design and Analysis of Overmoded RF Window for High-Power Applications in $X$ -Band

This article presents the design and analysis of overmoded RF window for megawatt-class pulsed coaxial magnetron operating in $X$ -band and other high-power systems such as linear accelerator (LINAC) and devices such as gyrotron and klystron. Three ingenious designs of RF windows are proposed based on the mode excitation techniques. Design 1 operates in TE012-type mode (mixed with TE113 and TE213), Design 2 in TE012-type mode (mixed with TE312), and Design 3 in TE014-type mode. Mixed-mode operation broadens the bandwidth of the RF window compared to single-mode operation. RF windows are simulated in CST and return losses are obtained as 55.04, 51.52, and 53.92 dB, and insertion losses as 0.054, 0.07, 0.194 dB, respectively. Return losses and insertion losses of the proposed designs are verified in HFSS, and results are in good agreement with the results obtained from CST. Coupled multiphysics analyses are carried out to study thermal and structural behaviors of the proposed RF windows. Sensitivity analysis of the windows is also performed to analyze the effect of mechanical deformation on the performance of S-parameters. Multipactor analysis is carried out to determine the safe operating power level, and multipactor thresholds are obtained as 10, 16, and 2.35 MW, respectively.

Design of Single disc RF window for High Power Gyrotron

In this paper investigates the design of water edge cooled single-disc CVD-diamond window for 120 GHz, 1MW gyrotron. The design of RF window for 120 GHz, 1MW gyrotron has been carried out using the CST microwave studio. In 120 GHz gyrotron single disc of diameter 90 mm and thickness 2.0 mm CVD diamond window has been used in the simulation. The return loss (S11) and transmission loss (S21) of the 120 GHz gyrotron window have been found – 40.0 dB and -0.02 dB respectively. Thermal analysis of single disc rf window has also been carried out using ANSYS software for high power 120 GHz gyrotron. The temperature range on the disc surface has been found to be 100°C–300°C.

Thermal Design of RF Window for High-Power Gyrotron

In this paper, thermal and structural analyses of an RF window for a 42-GHz 200-kW gyrotron have been carried out using ANSYS software and discussed in this paper. The evaluation of the thermal and structural aspects of the window for the 42-GHz gyrotron during an extreme case of operation, i.e., at saturation, has been carried out. Temperature profiles have been obtained for different values of dielectric loss. The temperature range on the sapphire disk surface has been found to be 30°C -68°C. The window performance has been found satisfactory.

Study of Cavity and Output Window for High Power Gyrotron

In this paper Eigen mode analysis has been carried out using Ansoft HFSS for high frequency 42, 120 and 140 GHz Gyrotron cavity. The design of RF window for 42 GHz, 200 kW Gyrotron has also been carried out using the Ansoft HFSS and CST microwave studio. In 42 GHz gyrotron double disc of diameter 85 mm and thickness 3.2 mm sapphire window and spacing (Coolant FC-75) of discs 2.5 mm has been used in the simulation. The return loss (S11) and transmission loss (S21) of the 42 GHz gyrotron window have been found −47.3 and −0.04 dB, respectively. The return loss and transmission loss of the S-band single disc sapphire window have also been found −27.3 and −0.07 dB, respectively at cylindrical waveguide length 33 mm. The simulated result has been validated through experimental results for pill-box S-band sapphire window.

CAD of RF Windows Using Multiobjective Particle Swarm Optimization

In this paper, computer-aided design (CAD) of two types of RF windows, namely, double-disk RF window and pillbox-type RF window, is presented for use in high-power microwave/millimeter-wave sources. The design of double-disk RF window was carried out for 42-GHz band (TE0,3 mode) and 170-GHz band (Gaussian mode), while the design of pillbox-type RF window was carried out for 2.856-GHz band. The requirement for the design of RF window is to minimize the reflections with exact matching at desired resonant frequency. In the present approach, a scattering-matrix code was invoked with recently developed particle swarm optimization (PSO) method in order to optimize the geometrical parameters of the window. Multiobjective optimizations using PSO have been used to achieve optimized tradeoff between matching of desired resonant frequency and minimizing the power reflections in the desired band of operation.

RF system research and development for the PEP-II B factory

The PEP-II B factory will be a high-luminosity asymmetric electron-positron collider optimized for the study of CP violation [1]. It is being built at SLAC by a collaboration including SLAC, LBL and LLNL. The integrated-luminosity needed for the experiment requires high average beam current in the two storage rings and this creates significant challenges in the design of the RF system and other components. The paper describes the R & D activities in progress towards meeting these challenges and some of the significant achievements in the areas of RF cavity design, higher-order mode damping, RF window design and feedback systems.