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Title: A High Power CW Input Coupler with Reduced Static and Dynamic Losses

Abstract

Each niobium cavity employed in superconducting accelerators requires a power coupler that supplies it with up to hundreds of kW’s of CW RF power, which is delivered to the 2K or 4K cold cavity from a Room Temperature (RT) source. Coupler design is a challenging task. It should transmit the minimum possible thermal power flow to the cavity, because a single watt at 2K requires 1 kW of cryogenic system power to remove it. Since the coupler connects the cold cavity to a Room Temperature (RT) power source, it transmits a static thermal load due to its thermal conductivity. Also, the coupler experiences heating by RF fields. This dissipated power partially penetrates to the 2K zone, and is called a dynamic load. From one point of view, the coupler should have low thermal conductivity, in order to decrease the static load. Stainless steel (SS) is usually used for that reason, but it also has low electrical conductivity, which introduces a high dynamic load. Copper plating on the SS is required to improve the electrical conductivity, but it is not reliable and often flakes. One copper flake might cause an electrical discharge and contaminate the surface of the niobium cavity, thusmore » spoiling its Q-factor. In that case, decommissioning of the entire cryomodule is required to restore the cavity Q-factor, which means it is a tremendously expensive procedure. That is why an improved reliability coupler is of very high interest. As a result, the main idea of the proposed project is to completely eliminate the unreliable copper plating by employing solid copper shields to screen the SS pipe from RF fields.« less

Authors:
 [1];  [1]
  1. Euclid Techlabs LLC, Cleveland, OH (United States)
Publication Date:
Research Org.:
Euclid Techlabs, LLC, Solon, OH (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1465728
Report Number(s):
DOE-Euclid Techlabs-PH1-17151
17151
DOE Contract Number:  
SC0017151
Type / Phase:
SBIR (Phase I)
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; Superconducting RF; accelerator; structures; coupler; plating; bellows

Citation Formats

Kanareykin, Alex, and Kostin, Roman. A High Power CW Input Coupler with Reduced Static and Dynamic Losses. United States: N. p., 2017. Web.
Kanareykin, Alex, & Kostin, Roman. A High Power CW Input Coupler with Reduced Static and Dynamic Losses. United States.
Kanareykin, Alex, and Kostin, Roman. Fri . "A High Power CW Input Coupler with Reduced Static and Dynamic Losses". United States.
@article{osti_1465728,
title = {A High Power CW Input Coupler with Reduced Static and Dynamic Losses},
author = {Kanareykin, Alex and Kostin, Roman},
abstractNote = {Each niobium cavity employed in superconducting accelerators requires a power coupler that supplies it with up to hundreds of kW’s of CW RF power, which is delivered to the 2K or 4K cold cavity from a Room Temperature (RT) source. Coupler design is a challenging task. It should transmit the minimum possible thermal power flow to the cavity, because a single watt at 2K requires 1 kW of cryogenic system power to remove it. Since the coupler connects the cold cavity to a Room Temperature (RT) power source, it transmits a static thermal load due to its thermal conductivity. Also, the coupler experiences heating by RF fields. This dissipated power partially penetrates to the 2K zone, and is called a dynamic load. From one point of view, the coupler should have low thermal conductivity, in order to decrease the static load. Stainless steel (SS) is usually used for that reason, but it also has low electrical conductivity, which introduces a high dynamic load. Copper plating on the SS is required to improve the electrical conductivity, but it is not reliable and often flakes. One copper flake might cause an electrical discharge and contaminate the surface of the niobium cavity, thus spoiling its Q-factor. In that case, decommissioning of the entire cryomodule is required to restore the cavity Q-factor, which means it is a tremendously expensive procedure. That is why an improved reliability coupler is of very high interest. As a result, the main idea of the proposed project is to completely eliminate the unreliable copper plating by employing solid copper shields to screen the SS pipe from RF fields.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2017},
month = {12}
}

Technical Report:
This technical report may be released as soon as August 22, 2022
Other availability
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