I’ve been curious about understanding the mechanism behind themionic emission from what I have read I found that themionic emission happen when the energy from added temperature excess the work function of the material. I also readed when temperature excesses 1000k themionic emission happens but when I calculate the energy in Ev from that temperature I get a number no where close to the work function of tungsten a material commonly used as filament for electron guns so what gives?(adsbygoogle = window.adsbygoogle || []).push({});

Wien Law

~~~~~~~~~~~2.89e-3

Wavelength =————-

~~~~~~~~~~~~1000k

Wavelength = 289e-8m

Conversation of wavelength to Joules

~~(6.626e-27)(3e10)

E=—————————

~~~~~~289e-8m

E=0.06878e-18

Joules to Electron volts

E = 0.06878e-18 * 6.242e18

E = 0.4293ev

Tungsten Workfunction = 4.5ev

I not sure if I’m just calculating the temperature with the wrong equation but those numbers don’t seem anywhere closes , when I used the work function of tungsten to calculate the temperature I get a number that is insanely high

Ev to wavelength

~~~~~~~~~~~(6.626e-34)(3e10)

Wavelength= —————————-

~~~~~~~~~~~~(4.5ev)/(6.242e18)

Wavelength = 2.757e-7

Wavelength = 275.7nm

Wien law

~~~~~~2.89e-3

T(k) = ————

~~~~~~2.757e-7

T(k) = 10482.408k

10482 KELVIN!!! that way excess the melting temperature of tungsten and that far exceeds the temperature in any electron gun if I am calculating the temperature wrong how do I do it properly and can anyone confirm that thermionic emission happens from temperature exceeding work function?

I read that thermionic emission happens from exceeding the work function of material from it Wikipedia page(I know it’s not the most credible site)

I also read that the temperature for thermionic emission of t > 1000k from Wikipedia also.

Sorry for any grammar mistakes I’m not a very good at spotting them

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# I How does thermionic emission work?

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