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Title: Choke Flange for High Power RF Components Excited by TE01 Mode

Abstract

A multifaceted program to study high gradient structures and properties of RF breakdown is under way at SLAC. This program includes testing of simplified versions of traveling wave and standing wave structures at 11.4 GHz. [Dolgashev] RF power is fed into these structures using a TE01 mode-launcher. An RF flange is used to connect the mode-launcher to the test-structure. The rf currents flow through either the stainless steel lip on the flange or, in an alternate assembly, through a copper gasket pressed between the same stainless steel lips. In a recent experiment with a single cell traveling wave structure, a flange with stainless steel lips was irreversibly damaged at RF power about 90 MW and {approx}100 ns pulse length. We suggest an alternative flange that does not rely on metal-to-metal contact in the rf power transfer region. The idea is to use an asymmetric choke flange, where the choke grove is cut into a conflate flange on the mode-launcher. The structures themselves will have a simpler, flat conflate flange with rounded corners on the vacuum side. The Vacuum seal is achieved with a Cu gasket between these two flanges above the RF region. We have designed a flange with amore » choke which is almost field free in the vacuum gasket region, whose technical specifications and RF properties are presented below. Design simulations were conducted using HFSS, a 3D finite element code that solves electromagnetic fields in complex structures. Figure 1 demonstrates the projected physical look of the choke flange, while the table next to it lists the critical parameters. The maximum electric field for in this geometry is on axis at 33.6MV/m for 100 MW input. The electric field near the gasket, meaning at the top of the choke gap is at 125kV/m or 1.25kV/cm. Figure 2 demonstrates the electric field strength profile in the geometry for 100 MW input power. The maximum magnetic field for in this geometry is near the pipe at 59kA/m for 100 MW input. The magnetic field at the gasket at the top of the choke gap is at 225A/m or 2.25/cm. Figure 3 demonstrates the magnetic field strength profile in the geometry for 100MW input power.« less

Authors:
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
969245
Report Number(s):
SLAC-TN-09-003
TRN: US1000265
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 43 PARTICLE ACCELERATORS; BREAKDOWN; COPPER; DESIGN; ELECTRIC FIELDS; ELECTROMAGNETIC FIELDS; FLANGES; GASKETS; GEOMETRY; MAGNETIC FIELDS; SPECIFICATIONS; STAINLESS STEELS; STANDING WAVES; STANFORD LINEAR ACCELERATOR CENTER; TESTING; Accelerators,ACCPHY

Citation Formats

Yeremian, A Dian, and /SLAC. Choke Flange for High Power RF Components Excited by TE01 Mode. United States: N. p., 2009. Web. doi:10.2172/969245.
Yeremian, A Dian, & /SLAC. Choke Flange for High Power RF Components Excited by TE01 Mode. United States. doi:10.2172/969245.
Yeremian, A Dian, and /SLAC. Fri . "Choke Flange for High Power RF Components Excited by TE01 Mode". United States. doi:10.2172/969245. https://www.osti.gov/servlets/purl/969245.
@article{osti_969245,
title = {Choke Flange for High Power RF Components Excited by TE01 Mode},
author = {Yeremian, A Dian and /SLAC},
abstractNote = {A multifaceted program to study high gradient structures and properties of RF breakdown is under way at SLAC. This program includes testing of simplified versions of traveling wave and standing wave structures at 11.4 GHz. [Dolgashev] RF power is fed into these structures using a TE01 mode-launcher. An RF flange is used to connect the mode-launcher to the test-structure. The rf currents flow through either the stainless steel lip on the flange or, in an alternate assembly, through a copper gasket pressed between the same stainless steel lips. In a recent experiment with a single cell traveling wave structure, a flange with stainless steel lips was irreversibly damaged at RF power about 90 MW and {approx}100 ns pulse length. We suggest an alternative flange that does not rely on metal-to-metal contact in the rf power transfer region. The idea is to use an asymmetric choke flange, where the choke grove is cut into a conflate flange on the mode-launcher. The structures themselves will have a simpler, flat conflate flange with rounded corners on the vacuum side. The Vacuum seal is achieved with a Cu gasket between these two flanges above the RF region. We have designed a flange with a choke which is almost field free in the vacuum gasket region, whose technical specifications and RF properties are presented below. Design simulations were conducted using HFSS, a 3D finite element code that solves electromagnetic fields in complex structures. Figure 1 demonstrates the projected physical look of the choke flange, while the table next to it lists the critical parameters. The maximum electric field for in this geometry is on axis at 33.6MV/m for 100 MW input. The electric field near the gasket, meaning at the top of the choke gap is at 125kV/m or 1.25kV/cm. Figure 2 demonstrates the electric field strength profile in the geometry for 100 MW input power. The maximum magnetic field for in this geometry is near the pipe at 59kA/m for 100 MW input. The magnetic field at the gasket at the top of the choke gap is at 225A/m or 2.25/cm. Figure 3 demonstrates the magnetic field strength profile in the geometry for 100MW input power.},
doi = {10.2172/969245},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2009},
month = {12}
}

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