Re: Creating plasma with microwaves?
Posted: Sun Oct 30, 2016 4:23 am
About that Doppler broadening of spectral lines, I ran some numbers Friday night but decided to hold off on posting them.
These are unreviewed!
Take, for example, the blue line of singly-ionized argon at 488 nm. Called 4880 Å when us oldsters were growing up.
At 300 K (room temperature), the thermal motion averages 0.026 eV per atom. RMS velocity is 508 m/s (293 m/s per axis, comparable to the speed of sound), and the FWHM linewidth from Doppler is 0.0007 nm.
At 10,000 K (0.86 eV per atom) it's 0.0039 nm.
At 100,000 K the kT energy reaches 8.6 whole eV, RMS velocity is about 9 km/s, and spectral linewidth due to Doppler is 0.012 nm.
Don't forget, we are talking about lightbulbs in MWO's, not fusors.
Ocean Optics USB4000 UV-VIS spectrometer normal optical resolution seems to be 1.5 to 2.3 nm FWHM. I saw somewhere that with a "plus" model, a resolution of 0.02 nm was attainable, but I think that needs more than just a narrow slit.
These are unreviewed!
Take, for example, the blue line of singly-ionized argon at 488 nm. Called 4880 Å when us oldsters were growing up.
At 300 K (room temperature), the thermal motion averages 0.026 eV per atom. RMS velocity is 508 m/s (293 m/s per axis, comparable to the speed of sound), and the FWHM linewidth from Doppler is 0.0007 nm.
At 10,000 K (0.86 eV per atom) it's 0.0039 nm.
At 100,000 K the kT energy reaches 8.6 whole eV, RMS velocity is about 9 km/s, and spectral linewidth due to Doppler is 0.012 nm.
Don't forget, we are talking about lightbulbs in MWO's, not fusors.
Ocean Optics USB4000 UV-VIS spectrometer normal optical resolution seems to be 1.5 to 2.3 nm FWHM. I saw somewhere that with a "plus" model, a resolution of 0.02 nm was attainable, but I think that needs more than just a narrow slit.