Study of Surface Field Enhancements due to Fine Structures

Study of Surface Field Enhancements due to Fine Structures Tetsuo ABE High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan TUPS086 Conclusions Field enhancements due to small grooves with round chamfers have been computed by using CST-MWS/EMS and FRW. - At least 20% enhancement for R=50mm round chamfers. - Increases to 40% enhancement as the D size increases to 25mm. - Agreements among the three methods. It has been demonstrated in this study that the FRW method gives high-precision calculations of local fields, and it is practical and promising because of its suitability for GPGPU computing. Rectangular Waveguide with f(TE10) = 10 GHz A small groove at the center of the E-plane Port mode computation of TE10 Hexahedral meshing with PBA Computation based on the FIT Using CST-MWS (RF) Using CST-EMS (E- Static) m ax Enhancem entFactor= ref E E ~ Two parallel PEC plates with a small groove Potential difference: 1.0V Hexahedral meshing with PBA Computation based on the FIT Floating Random Walk (FRW) m ax Enhancem entFactor= ref E E ~ 1000[V/m] ~ = Benchmark Test Introduction High-gradient radio-frequency (RF) accelerating structures are linchpins of high-energy accelerators to search for new physics in particle physics. However, fine surface defects in the structures, such as burrs from machining and undulations due to crystal structures, could increase surface fields and/or surface heating, and trigger breakdown of the accelerating structures, leading to deterioration of accelerator performance. As is well known, projection tips, or similar fine structures, can dramatically increase local surface fields. On the other hand, how much is field enhancement at fine concave structures? Such structures could be made at bonding planes, e.g. of quadrant-type X-band accelerating structures for CLIC. This is a problem presented in this paper, and surface-field enhancement factors are numerically calculated with three different methods: RF- and electrostatic-field simulations based on the Finite Integration Technique (FIT) and floating random walk (FRW). This algorithm is implemented in a computer program for GPGPU written in Fortran 2003 / CUDA Fortran. 1.0mm Schematic Diagram of FRW (adopted) (PEC) (Vac) (PEC)

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TUPS086. Using CST-MWS (RF). Using CST-EMS (E-Static). Rectangular Waveguide with f cutoff (TE10) = 10 GHz A small groove at the center of the E-plane Port mode computation of TE10 Hexahedral meshing with PBA Computation based on the FIT. Two parallel PEC plates with a small groove - PowerPoint PPT Presentation

Transcript of Study of Surface Field Enhancements due to Fine Structures

Study of Surface Field Enhancementsdue to Fine Structures

Tetsuo ABEHigh Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan

TUPS086

Conclusions

Field enhancements due to small grooves with round chamfershave been computed by using CST-MWS/EMS and FRW. - At least 20% enhancement for R=50mm round chamfers. - Increases to 40% enhancement as the D size increases to 25mm. - Agreements among the three methods.

It has been demonstrated in this study that the FRW method gives high-precision calculations of local fields, and it is practical and promising because of its suitability for GPGPU computing.

This FRW method is applicable to any structure.

Rectangular Waveguide with fcutoff(TE10) = 10 GHzA small groove at the center of the E-planePort mode computation of TE10Hexahedral meshing with PBAComputation based on the FIT

Using CST-MWS (RF) Using CST-EMS (E-Static)

maxEnhancement Factor = ref

Two parallel PEC plates with a small groovePotential difference: 1.0VHexahedral meshing with PBAComputation based on the FIT

Floating Random Walk (FRW)

maxEnhancement Factor = ref

~1000[V/m]

Benchmark Test

Introduction

High-gradient radio-frequency (RF) accelerating structures are linchpins of high-energy accelerators to search for new physics in particle physics. However, fine surface defects in the structures, such as burrs from machining and undulations due to crystal structures, could increase surface fields and/or surface heating, and trigger breakdown of the accelerating structures, leading to deterioration of accelerator performance.

As is well known, projection tips, or similar fine structures, can dramatically increase local surface fields. On the other hand, how much is field enhancement at fine concave structures? Such structures could be made at bonding planes, e.g. of quadrant-type X-band accelerating structures for CLIC. This is a problem presented in this paper, and surface-field enhancement factors are numerically calculated with three different methods: RF- and electrostatic-field simulations based on the Finite Integration Technique (FIT) and floating random walk (FRW).

This algorithm is implemented in a computer program for GPGPUwritten in Fortran 2003 / CUDA Fortran.

1.0mm

Schematic Diagram of FRW

(adopted)

(PEC)

(Vac) (PEC)