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Posted: Wed Nov 04, 2009 6:15 am
by Betruger
KitemanSA wrote:
alexjrgreen wrote:
KitemanSA wrote: No need to "claim" it. That fact has been stated in prior papers (or maybe it was just a posting).
Happy to be scooped if you can provide the link.
I did look back to try to find it, but couldn't in the time I was willing to spend. Basically I recall being told in one topic line that the bright glow in the WB7 picture in the EMC2 website was due to Helium being purposefully introduced at fairly high concentrations specifically to show the electron flow. Since the electrons flow withing the wiffleball and thru the cusps, QED. Best I can do for now.
I specifically remember that too.

viewtopic.php?p=5326#5326

viewtopic.php?p=19392&highlight=helium+wb7#19392

viewtopic.php?p=5377&highlight=helium+wb7#5377

viewtopic.php?p=7203&highlight=helium+wb7#7203
This last one is the one I think I was remembering.

Posted: Wed Nov 04, 2009 8:46 am
by MSimon
KitemanSA wrote:
alexjrgreen wrote:
KitemanSA wrote: No need to "claim" it. That fact has been stated in prior papers (or maybe it was just a posting).
Happy to be scooped if you can provide the link.
I did look back to try to find it, but couldn't in the time I was willing to spend. Basically I recall being told in one topic line that the bright glow in the WB7 picture in the EMC2 website was due to Helium being purposefully introduced at fairly high concentrations specifically to show the electron flow. Since the electrons flow withing the wiffleball and thru the cusps, QED. Best I can do for now.
I believe Helium was the test gas.

Posted: Wed Nov 04, 2009 8:56 am
by alexjrgreen
Betruger wrote:
KitemanSA wrote:
alexjrgreen wrote: Happy to be scooped if you can provide the link.
I did look back to try to find it, but couldn't in the time I was willing to spend. Basically I recall being told in one topic line that the bright glow in the WB7 picture in the EMC2 website was due to Helium being purposefully introduced at fairly high concentrations specifically to show the electron flow. Since the electrons flow withing the wiffleball and thru the cusps, QED. Best I can do for now.
I specifically remember that too.

viewtopic.php?p=5326#5326

viewtopic.php?p=19392&highlight=helium+wb7#19392

viewtopic.php?p=5377&highlight=helium+wb7#5377

viewtopic.php?p=7203&highlight=helium+wb7#7203
This last one is the one I think I was remembering.
Indrek suggested it first here:

viewtopic.php?p=5377&highlight=helium+wb7#5377

and was told it was lens glare...

So, in case people don't realise just how much information the WB7 picture is giving us, here's a summary.

The brightness in the WB7 picture is fluorescence caused by the interaction of electrons with a low vacuum filled with Helium. It tells us exactly where the electrons go.

The wiffleball is clearly visible as a well formed sphere in the centre and it has large circular holes opposite the middle of the coil faces. The corners are harder to see but there appear to be smaller circular holes in the wiffleball there.

The electrons stream out of the holes in the wiffleball towards the magrid and are prevented from reaching it by the magnetic field. After passing through the magrid they are decelerated by the electric field, accelerated back towards the magrid and returned to the wiffleball. This is what Dr Bussard meant by electron recirculation and it is visibly highly efficient.

This also shows very clearly why a permanent magnet can't be used.

At the corners you can see thin wisps of electrons escaping from the recirculation and hitting the support nubs between the coils.

Posted: Wed Nov 04, 2009 10:48 am
by KitemanSA
Nice summation.

Your eyes are better than mine, or else better trained! :wink:

Posted: Wed Nov 04, 2009 10:55 am
by Betruger
Yeah, I can't pick out nearly that much detail either.
Image
Limit of information before artifacts:
Image

Posted: Wed Nov 04, 2009 2:33 pm
by alexjrgreen
Betruger wrote:Yeah, I can't pick out nearly that much detail either.
The two broad lines on the left are reflections in the side of the viewing window. The thin line at the back is a reflection from a vacuum chamber seam.

The electron jet from the coil centre hole is clearly visible and extends some distance beyond the coil. A very light fan-shaped dusting shows the small number of electrons that didn't get turned round by the magrid.

The jet from the corner hole facing directly outwards is harder to see but is visible from its reflection in the coil casings. It doesn't appear to extend beyond the magrid.

Posted: Wed Nov 04, 2009 3:21 pm
by Betruger
Thanks Alex. How do you know for sure that the wiffle ball in the core light has formed and is as you described?
The wiffleball is clearly visible as a well formed sphere in the centre and it has large circular holes opposite the middle of the coil faces.

Posted: Wed Nov 04, 2009 4:02 pm
by alexjrgreen
Betruger wrote:Thanks Alex. How do you know for sure that the wiffle ball in the core light has formed and is as you described?
The wiffleball is clearly visible as a well formed sphere in the centre and it has large circular holes opposite the middle of the coil faces.
The sphere you can see. Zoom away from the picture to make it obvious. The holes are clearly there because you can see an electron jet coming out of one.

Do you recall Indrek's model?

Posted: Wed Nov 04, 2009 5:17 pm
by TallDave
Hey, good catch guys. There was an argument a while back about how spiky vs. spherical the WB would be. If the picture is any kind of indication it's a quasisphere with spikes coming out.

Posted: Wed Nov 04, 2009 5:32 pm
by alexjrgreen
TallDave wrote:Hey, good catch guys. There was an argument a while back about how spiky vs. spherical the WB would be. If the picture is any kind of indication it's a quasisphere with spikes coming out.
Better than spikes. Electron recirculation.

Posted: Wed Nov 04, 2009 6:50 pm
by Betruger
I remember pretty much every picture ever posted, but I'm not sure who made what. I'll have to go dig them up again and compare this one with Indrek's.

Posted: Wed Nov 04, 2009 9:38 pm
by alexjrgreen
Betruger wrote:I remember pretty much every picture ever posted, but I'm not sure who made what. I'll have to go dig them up again and compare this one with Indrek's.
viewtopic.php?p=8044&highlight=#8044

Posted: Wed Nov 04, 2009 10:40 pm
by D Tibbets
alexjrgreen wrote:
Betruger wrote:Yeah, I can't pick out nearly that much detail either.
The two broad lines on the left are reflections in the side of the viewing window. The thin line at the back is a reflection from a vacuum chamber seam.

The electron jet from the coil centre hole is clearly visible and extends some distance beyond the coil. A very light fan-shaped dusting shows the small number of electrons that didn't get turned round by the magrid.

The jet from the corner hole facing directly outwards is harder to see but is visible from its reflection in the coil casings. It doesn't appear to extend beyond the magrid.
I'm not sure what relflection is at the ~ 9 o'clock position. The vertical line might be a reflection off a coil or the vacuum chamber wall. The almost horizontal line looks like one of the spikes. Unfortionatly the window cuts it off just where recirculation might be kicking in. The spike at the ~ 2 o'clock position does look like a nice spike witha sharp transition region. It may show the geometry of the Wiffleball cusp, though I wonder if it is as tight as an optomial wiffleball would be. The metal rod on the left is, I assume, the gas puffer (or possibly a cathode)and it looks like an arc is already ocurring, in which case the Wiffleball may already be breaking down. I agree that it looks like the cusp throats make up only a small portion of the wiffleball surface.
With the resolution of the picture and the contrast, I really cannot see any detail reaching the magrids (concentrating on the spike at the 2 o'clock position), so I don't think anything can be said about recirculation.

Dan Tibbets

Posted: Wed Nov 04, 2009 11:25 pm
by alexjrgreen
D Tibbets wrote:The metal rod on the left is, I assume, the gas puffer (or possibly a cathode)and it looks like an arc is already ocurring, in which case the Wiffleball may already be breaking down.
I don't see this, so I'm curious what you're referring to.

Posted: Thu Nov 05, 2009 2:13 am
by MSimon
Keep in mind that the experiment is a pulsed one and that it does not produce much light.

I do see the "oscillations" and the Indrek surface. But without data one must retain the possibility that we are seeing what we want to see.