Fritz Krause (physicist)

Fritz Krause (* 1927 in Großsärchen ) is a German mathematician and astrophysicist .

Life

Gustav Emil Fritz Krause attended the Pedagogical College in Gotha from January 1946 and went from there to study at the Friedrich Schiller University in Jena . He passed his matriculation examination in 1947 at the university's preparatory school, but began studying mathematics with Walter Brödel and physics with Friedrich Hund in the winter semester of 1946 . The mathematics studies were completed in 1951 with the thesis "The Poncelet Polygons". The doctorate took place in 1958 under Walter Brödel with the thesis "On the conformal geometry of the triple orthogonal systems" at the Institute for Pure Mathematics.

In 1958 Krause became a research assistant at the Institute for Magnetohydrodynamics Jena of the German Academy of Sciences in Berlin under the direction of Max Steenbeck . Here he first worked on low pressure plasmas and the thermodynamics of irreversible processes, later on the origin of cosmic magnetism as a result of a universal magnetohydrodynamic dynamo process . As part of this work, he completed his habilitation in 1968 at the Faculty of Mathematics and Natural Sciences at the University of Jena with the thesis "A solution to the dynamo problem on the basis of a linear theory of magnetohydrodynamic turbulence".

From 1972 Fritz Krause headed the department “Physics of Cosmic Magnetic Fields” at what was then the Central Institute for Astrophysics in Potsdam, which also included departments for photometry and spectroscopy of magnetic stars. He has been a member of the German Academy of Sciences Leopoldina since 1980 . Since then he has been a member of the editorial board of the journal Astronomische Nachrichten for many years .

Scientific work

Fritz Krause developed the mathematics of the dynamo theory of cosmic magnetic fields and applied it to planets , stars and later also galaxies . The mathematical methods for electrodynamics of turbulent media presented in the first publications developed at the start of numerous later studies by other authors. The publications, which were originally written in German, were translated into English by PH Roberts and M. Stix soon after their appearance and have since been one of the cornerstones of the now independent branch of science dynamo theory. The names introduced at that time (α-effect, α-Ω dynamo, screw sense ) are mostly still in use today.

The new idea that emerged from mathematics was that in turbulence with a preferred screwing sense - as it generally exists in rotating celestial bodies - the stochastic movements not only destroy large-scale magnetic fields, which was already known, but also generate them simultaneously via the α effect. The basic equation of electrodynamics modified in this way allows solutions with large-scale magnetic fields of dipole or quadrupole geometry, which - as has been done in astrophysics and geophysics for centuries - can be measured outside. Depending on the strength of the differential rotation inside the celestial bodies, constant or alternating field dynamos are formed, which differ greatly from one another in terms of their temporal behavior and the geometry of the induced magnetic fields.

The magnetic fields of galaxies , the interior of which is well known through direct observations, are a special case . Under the influence of the galactic rotation, the vertically strongly stratified interstellar turbulence leads to a complicated tensorial α-effect, which in interaction with the differential rotation and the galactic wind ("galactic fountains") generates extensive quadrupole-type magnetic fields, as they are also observed . An as yet unsolved problem is the origin of the necessary weak seed fields, which must not have the wrong symmetry.

Books

• with K.-H. Rädler: Electrodynamics of the mean fields in turbulent conductive media and dynamo theory. In: R. Rompe, M. Steenbeck (Hrsg.): Results of plasma physics and gas electronics. Volume II, Akademie-Verlag, Berlin 1971.
• with K.-H. Rädler: Mean-field magnetohydrodynamics and dynamo theory. Pergamon Press, Oxford / Akademie-Verlag, Berlin 1980.
• with K.-H. Rädler and G. Rüdiger: The cosmic dynamo. Proceedings of the 157th International Astronomical Union Symposium. Kluwer, Dordrecht 1993.

Individual evidence

1. ↑ Member entry of Fritz Krause at the German Academy of Sciences Leopoldina , accessed on February 1, 2016.
2. ↑ M. Steenbeck, F. Krause: Explanation of stellar and planetary magnetic fields by a turbulence-induced dynamo mechanism. In: Journal for Nature Research . 21, 1966, p. 1285.
3. ↑ M. Steenbeck, F. Krause, K.-H. Rädler: Calculation of the mean Lorentz field strength for an electrically conductive medium in turbulent motion influenced by Coriolis forces. In: Journal for Nature Research. 21, 1966, p. 369.
4. ↑ M. Steenbeck, F. Krause: On the dynamo theory of stellar and planetary magnetic fields. I. AC dynamos of solar type. In: Astronomical News . 291, 1969, p. 49.
5. ↑ M. Steenbeck, F. Krause: On the dynamo theory of stellar and planetary magnetic fields. II. DC dynamos of planetary type. In: Astronomical News. 291, 1969, p. 271.
6. ^ F. Krause, R. Wielebinski: Dynamos in galaxies. In: Reviews in modern astronomy. 91, 1991, p. 260.
7. ^ F. Krause, R. Beck: Symmetry and direction of seed fields in galaxies. In: Astronomy and Astrophysics . 335, 1998, p. 789.