We record with sadness the death of Franz Kahn, a former Associate Editor of the Journal of Plasma Physics.

Franz was born in Germany in 1926, but his family emigrated to England in 1938. He attended Oxford University, obtaining First Class Honours in Mathematics in 1947, and continuing as a research student there, eventually gaining his D.Phil. in 1950. His thesis work already involved him in plasma physics, under one of the pioneers of the subject. His supervisor was Sydney Chapman, and his topic was that of the production of plasma by solar flares, and its interaction with the Earth's atmosphere. This field had already been opened by Chapman and a previous pupil, Vincent Ferraro, in the 1930s. The idea had originally been phrased in terms of ‘corpuscles’, i.e. energetic ions and electrons, but it had gradually been realized that electrostatic forces give such a medium a coherence, so that it should be described as a fluid, notwithstanding the lack of collisions. This is of course the basic idea of plasma physics, and when the importance of magnetic fields was included, one had all the ingredients of magnetohydrodynamics.