🚀 go-pugleaf

In article <1630@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes:
>	I don't know anything about the above Russian device, but I can
>comment about a "thermal battery" which was developed during World War II
>for use as a power source for electronic proximity fuses used in artillery
>shells and rockets.
>	This thermal battery consisted of two thermopiles (i.e., an array of
>thermocouple junctions in series-parallel): one for low-voltage, high-current
>for filament power, and the other for high-voltage, low-current for plate B+
>power.  The thermopiles were powered by the hot exhaust gases and burning
>propellant of mortar shells, anti-submarine rockets, etc. 
>	The thermal battery is an interesting device since it must be capable
>of several years shelf-life, but yet be ready for instant use with a high
>degree of reliability.  The actual operational life of the battery is usually
>measured in seconds.

A more common form of the military thermally actuated battery is a conventional
primary cell with a solid salt as an electrolyte.  A pyrotechnic charge is used
to melt the salt immediately prior to use.  The primary use of this battery is
in applications as described above: many years of shelf life with almost no 
degree of degradation, high reliability, and high power density.  With a solid
salt electrolyte, ion mobility and kinetics are nil.  Once the salt is molten,
ion mobility is good and the reaction kinetics are quite high.  Pyrotechnic
igniters have shown a high degree of operating reliability.  Power density is
good at the high temperatures involved.  Operating life of these batteries is
usually less than one hour and often several minutes.
                                       Barry