Conducted EMI Reduction on the Pulse Tube Cryocooler

Author

Eshraghi, M.J. ; Cho, Myongwon ; Kim, Jin Mok ; Sasada, Ichiro

Author_Institution

Dept. of Appl. Sci. for Electron. & Mater., Kyushu Univ., Kasuga

Volume

45

Issue

6

fYear

2009

fDate

6/1/2009 12:00:00 AM

Firstpage

2754

Lastpage

2757

Abstract

Pulse tube (PT) cryocoolers can be used to cool SQUIDs, however their electromagnetic interference (EMI) through the conducted high frequency noise currents are normally too large to operate SQUIDs. In this paper, high frequency noise currents of a pulse tube cryocooler system are simultaneously observed at several critical points to analyze conducting paths of the noise currents and to find a solution for this problem. High frequency noise currents are detected by current sensors consisting of a current transformer and a terminating resistor at the secondary side. By covering three-phase power lines and a neutral line connecting the valve motor to the inverter with a copper mesh, and by using it as an additional neutral line, conducted EMI (noise currents) to the cryostat has bee reduced by one fifth. With this treatment, SQUIDs have been operated normally.

Keywords

SQUIDs; cryogenics; electromagnetic interference; magnetic cooling; valves; SQUID; conducting paths; copper mesh; current sensors; current transformer; electromagnetic interference; high frequency noise currents; neutral line; pulse tube cryocooler; terminating resistor; three-phase power lines; valve motor; Electromagnetic interference; SQUIDs; high frequency current sensor; noise measurement; pulse tube cryocooler;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2009.2020548

Filename

4957755