Flux concentrator has high primary to secondary coupling efficiency enabling it to produce high magnetic fields. The device provides versatility in pulse duration, magnetic field strengths and power sources

Bailey, B. M.

Brechna, H.

Hill, D. A.

English

NASA Technical Reports Server

Radi	 '' -
Threaded 
Grooves Primary 
Winding 
nnulus 
I ng 
Stacked Coaxial Disks 
November 1969	 Brief 69-10654 
..
	
AEC-NASA TECH BRIEF 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Cryogenic Flux-Concentrator 
The problem: 
To develop a flux-concentrator for producing high 
magnetic fields. Various apparatus have been used, 
such as systems employing a hollow, metallic, secon-
dary, cylindrical flux-concentrator, wrapped with 
primary conductor turns in which a high-frequency 
voltage is applied. These systems produce the desired 
concentration of flux, but the coupling between the 
primary and secondary elements is low because a very 
large amount of the applied ampere turns to the flux-
concentrator is wasted in fringing fields.
The solution: 
A flux-concentrator magnet having primary and 
secondary windings for producing a high magnetic 
field. A high primary-to-secondary coupling efficiently 
produces high magnetic fields of from 100 to 150 kOe. 
The device provides versatility for a wide variety of 
pulse durations, applications, magnetic-field strengths, 
and power sources; it is constructed of -simple, effi-
cient, interchangeable, prefabricated components. 
In tests, the magnet and flux-concentrator have 
survived 400,000 pulses at peak power input of 1.6 
MW, a peak current of 3850 A with a primary winding 
of 208 turns, pulse duration of 50 msec having a high-
field duration above 80% of peak for 40 msec, a 
repetition rate of one pulse per 3 sec, an average 
power input of 24 kW, an energy input of 73 kJ per 
pulse, and a field of at least 100 kOe. 
How it's done: 
The cryogenic flux-concentrator magnet has 6 pri-
mary winding and an inner secondary winding that 
interact to produce a higher field in the bore of the 
secondary winding than is produced in the bore of the 
primary winding alone. The flux-concentrator has 
stacked disks forming radial slits, with removable 
prefabricated coils between each pair of disks. 
The figure shows a partial cross section of the flux-
concentrator with individual primary, prefabricated 
coils interposed between a plurality of coaxial disks 
forming a secondary cylinder. The stacked coaxial 
disks can be put together in any shape desired. The 
number of turns and the primary winding can be 
matched to any power supply. 
The disks are provided with stainless-steel clamps 
for selective stacking and unstacking to resist the 
tendency of the magnetic field to expand the bore. The 
(continued overleaf) 
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Administration. Neither the United States Government nor any per-
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radial slits in disks are sequentially spaced progres-
sively in rotation from one another by 600. 
The concentrator has a laminated iron core outside 
the flux-concentrator and in an unused portion of the 
bore to increase the magnetic field in the bore. Liquid 
nitrogen is the cryogenic coolant for the primary 
winding. 
Notes: 
I. Further information is available in Patent Disclo-
sure 3,384,849, U.S. Patent Office, 21 May 1968 
2. This innovation may interest manufacturers of 
superconducting magnets and researchers in 
nuclear physics. 
3. Inquiries concerning this innovation may be di-
rected to: 
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B69-10654
Source: H. Brechna, D. A. Hill, and B. M. Bailey of

Massachusetts Institute of Technology

under contract to

Argonne National Laboratory

(ARG-10494) 
Patent status: 
Inquiries concerning rights fr commercial use of 
this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439 
Brief 69-10654	 Category 02


Cryogenic flux-concentrator

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