JLN's Logbook gives a wealth of information on how the
tube filament is constructed etc.
For instance, if the filament was straight it would have a resistance of
~ 160 ohms at 2200 K (1.25 times this at 2700 K) but, his calcs show 0.1 ohms indicating that
the "zig-zag" mounting has about 80 "cycles". Also he neglects
the ~380 watts of radiated power lost from the filament at 2200 K and ~990 watts at 2700 K
if not cycled at 5% of the 50 "Hz" rep rated .
IOW, if it was pulsed with a 5% - 50 Hz duty cycle square wave the filament would be on for
~1.0 millisecond and off for ~ 19 milliseconds.
With 0.5% production of monatomic H at 2200 K (if it ever got there) it's
hard to see anything other than calorimetry error. IMHO.
FJS
