Re: Nicholas Moller on Langmuir

[Bob Fickle]

I've made no assumption regarding input power, except to comment that it's not enough to heat the filament- based solely on the specific heat of tungsten.  To supply 200 Joules in a 10-ms pulse, for example, would require a power of 20 KW.  Ain't happening. George Holz wrote: Bob Fickle wrote: I have " ...attempted to estimate how fast the filament will heat up". From the description on JLN's web page, I estimate the filament has a mass of about 1.2g, and would require about 200 Joules to heat from an average temperature of ~700K to the "operating" temperature of 2000K. The input during the short pulses is much less than this. I posted this calculation to JLN about 10 days back, but have no reply as yet. What assumptions did you make to allow the calculation of input power during the pulse? Are the numbers that JLN reports actually average voltage and current as the labels, now changed, on his web site once indicated? If they are, the input power calculations are low by a factor of 1/(duty cycle) or about 20 and the system actually is close to unity. George Holz Varitronics Systems