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Cryogenic system of the MAX-Wiggler

På svenska

Author

  • Erik Wallén
  • Gregory LeBlanc

Summary, in English

A novel insertion device for electron storage rings called the MAX-Wiggler has been constructed and commissioned at MAX-lab. The MAX-Wiggler is a cold bore superconducting wiggler magnet with 47 3.5 T poles and a period length of 61 mm aimed for the production of X-rays at the 1.5 GeV electron storage ring MAX-II at MAX-lab. This note describes the cryogenic system of the MAX-Wiggler, theoretical predictions of the heat loads to the cryostat, and measured heat loads at operation. The cryostat is a helium cooled bath type cryostat. The design criterion for the cryostat was to have a liquid He boil-off less than 3 1/h, which corresponds to a heat load of 2.1 W. The theoretical calculations predicted a heat load of 0.87 W to the liquid He bath. Of the 0.87 W predicted heat load, 0.17 W was predicted to be induced by the stored beam in MAX-II, 0.12 W from synchrotron radiation and 0.05 W from image currents. The measured heat load to the liquid He bath is larger than predicted from the theoretical calculations and at nominal working conditions it is 1.7 W. The measured contribution to the total heat load from the stored beam of 200 mA in MAX-II is 0.86 W, 0.59 W from image currents and 0.26 W from synchrotron radiation. The measured contribution from the image current is 0.59 W, about 10 times larger than expected from the theoretical calculations, which is assumed to depend on that the Cu plating of the inner surfaces of the cold bore has a lower electrical conductivity than foreseen. The higher than expected heat load from synchrotron radiation is assumed to come from a positioning error of the upstream absorber for synchrotron radiation. There is no observable increase of the heat load with the wiggler at full field. Even though the heat loads are higher than expected, the design criterion of obtaining a cryostat with a liquid He boil-off inferior to 3 1/h with 200 mA of stored current in MAX-II has been met. (C) 2004 Elsevier Ltd. All rights reserved.

Department/s

Publishing year

2004

Language

English

Pages

879-893

Publication/Series

Cryogenics

Volume

44

Issue

12

Document type

Journal article

Publisher

Elsevier

Topic

  • Physical Sciences
  • Natural Sciences

Keywords

  • synchrotron radiation
  • image currents
  • superconducting wiggler
  • cold bore
  • insertion device

Status

Published

ISBN/ISSN/Other

  • ISSN: 0011-2275