First progress report on a multi-channel magnetic drum inner ...

lT-3
these are essentially the useful inderction "1". The leakage inductance
"L" consists of all flux lines which can couple the current stream in
the conductor in the space without the surface; minimizing the separation
"d" clearly also reduces this unwanted term.
5) Many over-simplifications exist in the above excimple, but it
is thought that the implied conclusion is substantially true; namely,
that throughout a significant range of useful conditions the best
ratio of l/L is obtained by means of a single conductor of small
diameter held as close as possible to the primary magnetic recording
surface. If, for exaimple, a prototype geometry of this sort be used
on a magnetic core which in turn acts on the recording surface, then
additional leakage "L" is contributed by the core throughout its length
and especially where the core relays the flux to the recording surface.
If a multi-turn conductor system is compared, new leakage terms due to
mutual inductancas.'-'are ixritiroduceds— -"
L' = Li + L2 + 2Ui2
Special circumstances can certainly modify these implications, such as the
possibility of more completely surrounding the conductors by magnetic
material. Discussion of these variants will be undertaken at a later
occasion.
6) The local field required to magnetize typical commercial mag-
netic recording materials, which have a coercive force in the vicinity