Re: [Phys-L] plasma sphere

[Dan Beeker <debeeker@comcast.net>]

Electromagnetics/electrostatics was not one of my strong points in 
school so I  may have to do a little hand waving. And I suspect  I'll be 
eating humble pie before this thread dies.

In the plasma globe the electric field oscillates at some tens of 
kilohertz. But the field is essentially spherical (ignoring the base).

One can consider the outer glass sphere as a dielectric with a plasma 
conducing inside the glass and air conducting outside the glass. Perhaps 
(I hand wave here) we can call it a capacitor? Regardless, there is a 
constant areal density em field at the outer globe. Now put you finger 
near, or on the globe. Compared to the air outside the globe your finger 
is a very low impedance to ground (through your body). The lower 
impedance means more energy (more current?) will flow through the outer 
glass near your finger. I surmise the electrons move faster near you 
finger. The greater energy causes the electrons (don't ask me which 
ones) move to a higher energy level, hence giving off a different energy 
photon when they return to their ground state. My original intention was 
to say one could use a spectrometer to look at the plasma discharge and 
determine  the gas(ses) in the globe and the specific energies of the 
photons. And doesn't e = h nu? So the blue color has higher energy than 
the orange? Whoops, that's backwards (I think). Orange is near the outer 
globe, blue is towards the center so my logic is backwards. I've been 
tooting my horn and haven't really thought about physics much the last 
few months (years?). So I quit rambling now. I'll let others jump in and 
bail me out (or bury me deeper ;-)

Dan

On 10/25/2024 4:15 PM, Sam Sampere wrote:
> Why do e- have higher energies near the glass wall?
>
> -----Original Message-----
> From: Phys-l <phys-l-bounces@mail.phys-l.org> On Behalf Of Dan Beeker via Phys-l
> Sent: Friday, October 25, 2024 1:26 PM
> To: phys-l@mail.phys-l.org
> Cc: Dan Beeker <debeeker@comcast.net>
> Subject: Re: [Phys-L] plasma sphere
>
> Perhaps we could put a little science to work here. Makes sense the electrons have higher energy near the outer glass. Can we determine this experimentally? We all know electrons in the lamp are excited. We also know a photon is emitted when an electron loses energy and “falls” (transitions) to a lower energy level. We observe bluish and pinkish colors. Most of us have spectroscopes. Perhaps one could look at the emission and determine what gases are prevalent inside the globe? Then look at the bluish emission only to ascertain which energy level the electrons are “falling” to? Then do the same for the pinkish emission. Which has the greater energy drop?
>
> Iirc astronomers do this a lot.
>
> > > .
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