The Karlqvist gap or Karlqvist Field is an

electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions of a ...

phenomenon discovered in 1953 by the Swedish engineer Olle Karlqvist (1922-1976), which is important in

magnetic storage Magnetic storage or magnetic recording is the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetisation in a magnetizable material to store data and is a form of non-volatile memory. The information is acc ...

for computers. (HTML 1 kB) Karlqvist discovered the phenomenon while designing a

ferromagnetic Ferromagnetism is a property of certain materials (such as iron) which results in a large observed magnetic permeability, and in many cases a large magnetic coercivity allowing the material to form a permanent magnet. Ferromagnetic materials ...

surface layer to the magnetic

drum memory Drum memory was a magnetic data storage device invented by Gustav Tauschek in 1932 in Austria. Drums were widely used in the 1950s and into the 1960s as computer memory. For many early computers, drum memory formed the main working memory ...

for the

BESK BESK (''Binär Elektronisk SekvensKalkylator'', Swedish for "Binary Electronic Sequence Calculator") was Sweden's first electronic computer, using vacuum tubes instead of relays. It was developed by '' Matematikmaskinnämnden'' ( Swedish Boar ...

computer. (HTML 3 kB) When designing a magnetic memory store, the ferromagnetic layer must be studied to determine the variation of the

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

with permeability, air gap, layer thickness and other influencing factors. The problem is

non-linear In mathematics and science, a nonlinear system is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathematicians, and many other ...

and extremely difficult to solve. Karlqvist's gap discovery shows that the non-linear problem could be approximated by a linear boundary value for the two-dimensional static field and the one-dimensional transient field. This linear calculation gives a first approximation. Karlqvist published his discovery in the 1954 paper "Calculation of the magnetic field in ferromagnetic layer of a magnetic drum" at

KTH Royal Institute of Technology The KTH Royal Institute of Technology ( sv, Kungliga Tekniska högskolan, lit=Royal Institute of Technology), abbreviated KTH, is a public research university in Stockholm, Sweden. KTH conducts research and education in engineering and technolo ...

in Stockholm. (PDF 741 kB)

References

{{Computer-stub Electromagnetism Computer memory

See also

References