American Magnetics Current Leads for Cryogenic Systems Brochure - Manual (Page 6)

OTHER TYPES OF CURRENT LEADS
HIGH TEMPERATURE SUPERCONDUCTOR (HTS) LEADS
HTS leads are available on a custom basis in both Vapor Cooled or Conduction Cooled versions. The most
commonly used conductor material is BiSCCO 2223 doped with a Au/Ag alloy. In cryogenic systems with
liquid helium the vapor cooling of the HTS section with helium gas provides low losses, high current density
and good system stability. The transition from the warm end of the HTS lead to ambient temperature is
made using conventional AMI leads cooled with a forced flow of liquid nitrogen. In systems operating in a
vacuum environment the HTS lead is conductively cooled with a mechanical refrigeration system
(cryocooler).
BREAK-AWAY LEADS
The Break-Away option allows the leads to be manually retracted once the magnet is in the persistent
mode. This essentially eliminates the heat load from the leads and minimizes the liquid helium boil off.
This type of lead is ideal for systems operating in persistent or standby mode for long periods of time.
Leads of this type are available up to 1000 Amps.
The mechanical and electrical
connection between the lower
end of the current lead and the
superconducting bus bar is made
with a low resistance socket-to-
post connection. The male post is
mounted onto an insulated support at the lower end of the cryostat neck region. The female socket is
integral to the lead and slides up and down within a guide tube to ensure proper alignment. Multi-
conductor wands are also available for NMR style systems requiring multiple shim coil operation.
FLEXIBLE BREAK-AWAY LEADS
Helium gas cooled leads are available in a flexible package that is self-
contained and self-supporting. The leads are straight in the relaxed
position and rigid enough to easily connect/disconnect from the cold end
current post. This option allows the leads to be bent as they are inserted
or retracted where restrictions such as low ceiling height are an issue.
This is yet another example of innovative current lead design.
SPECIAL APPLICATION LEADS
Some applications require special considerations and AMI has
the ability to provide solutions for these as well. Examples of
such applications include radial array lead clusters, Alternating
Current (AC) systems, leads for cryogenic systems using
nitrogen gas cooling, and leads operating in a vacuum space
with force fed helium gas cooling. Helium reservoirs with level
controls are available as an integral part of the current lead
construction for vacuum space installations. Coaxial leads can
be provided to reduce system penetrations when needed.
HTS Lead