Helium Plasma Reaction: Magnetic Field Impact

[Physicist50]

Hello everyone, I was recently creating two different types of plasma for a Science Fair, one created from ionised Helium, (although it's the party balloon stuff, and I hear there's some Oxygen in them) and the other was created from air. I was testing how the plasmas reacted to magnetic fields. Upon ionisation, both plasmas moved a little, but when the magnet was introduced, both swayed and moved much more. Interestingly enough, the Helium one jiggled frantically, noticeably more than the air one, and I was wondering why this happens.

Thanks in advance

 

[Simon Bridge]

You'll want to compare notes:
https://www.physicsforums.com/showthread.php?t=767284
... meantime, I'll think about it.

Off the top of my head: helium is a lot lighter so will respond to small changes in the electric and magnetic field more strongly, as well as the pressure variations in the inflowing air.

 

[Physicist50]

You'll want to compare notes:
https://www.physicsforums.com/showthread.php?t=767284
... meantime, I'll think about it.

Off the top of my head: helium is a lot lighter so will respond to small changes in the electric and magnetic field more strongly, as well as the pressure variations in the inflowing air.

Thanks Simon Bridge, but I'm still not sure I understand. Why would the weight of Helium affect how it reacts to magnetic fields? Sure, it affects how it reacts to gravity differently, but to my knowledge the two phenomena are not related.

 

[Simon Bridge]

The atomic weight ... related to the charge on the nucleus and the number of electrons it has. This affects the ionization energy. The mass of a particle in a box affects it's specific heat capacity - i.e. how it responds to heating, where the heat energy can get used. It's quantum.

Weight also affects buoyancy - which is important to your experiment - and is related to inertia, which goes to how the atoms respond to small pressure changes like fluctuations from uneven heating in the gas, and air flow from under the container.

 

[rufusgwarren]

It would help to have more data collected for the plasma, and data under multiple conditions, temperature, any temperature variations on the two samples, the mass of each sample, how ionization took place, a description of the container, and the magnetic field strength and shape. I suspect the vibration was caused by the field within the plasma and how it responded to the magnetic field. We can visualize the field for a steady unidirectional magnetic field and the motion of the protons. It would interesting if more was at play, i.e. If one considers the neutron to be a proton with a captured electron, then the states of this configuration within the atom under the condition mentioned could be enlightening. So to understand what is going on, only a guess, for me, at this time; but, with more data, we could define an hypothesis. Since the entire atom was in motion, I would suspect that the polarity of the nucleus, i.e. what's happening with the trapped two electrons, causes these difficult to measure dipoles to flip. So you might have a breakthrough on measuring the effects of the dipole moment within the nucleus of helium under ... conditions.

 

[Simon Bridge]

@rufusgwaren: welcome to PF - nice 1st post.
I have a feeling that the setup is similar to the other thread linked in post #2.
I x-linked from there too so replies need only go in one place.

The experiment is qualitative with very little control of variables.
The suggestions about what could be achieved with more data would make a good conclusion to the summary to the experiment write-up.

I don't think a microwave oven (OP has yet to confirm the method) delivers enough energy to make a plasma though - could the glowing stuff just be normal florescence? The match adds carbon and phosphor compounds into the gas mix.

 

[rufusgwarren]

yea, i see, could just be a modal response from the microwave. Yet, needs a little bit more science.

 

[Simon Bridge]

Looking further - see "Townsend avalanche".
The match provides an initial plasma (flame) and the microwaves ensure the ions don't recombine quickly - instead, collisions with the gas in the glass ionizes it, and also excites it's electrons. If this is correct then the glow is a mix of regular hot gas and plasma.

So back to standard:
There are a lot of sources for fluctuations in the experiment.
Heavier gasses will respond more sluggishly.
See notes other thread.

Finally found a paper: http://pubs.acs.org/doi/abs/10.1021/ac00235a026
Seems helium is particularly good at this.