Fun with accelerators

On Thursday, August 19, 2021 at 2:52:22 PM UTC-7, John Miles, KE5FX wrote:
> On Thursday, August 19, 2021 at 12:07:05 PM UTC-7, DecadentLinux...@decadence.org wrote: 
> > I was developing a 50kV supply for an X-Ray machine once and one of 
> > my co-engineers did a demo for us. We test un-potted in a Fluorinert 
> > bath. He took a long stick and placed a rounded nose "probe" on the 
> > end of it and a long HV wire to ground. As he approached the 
> > energized supply output buried in the bath, the bath started jiggling
> > furiously on the surface.... 
> 
> Hmm. Makes me wonder if a circulating loop of Fluorinert or SF6 could 
> be used to replace the belt in a Van de Graaff machine. 

The charging of Fluorinert would be problematic; if you added some particles
of something conductive, and a dye that is photoconductive, you could
UV-illuminate at the current injection site, conduct charge in that region,
and when the conductivity wanes (with time, in darkness) the particles
would hold charge and be swept with the Fluorinert current.  Without 
particles, the charge might 'track' in any pipe materials it contacts rather
than going with the flow.

The alternative would be field-emission points in the liquid flow;
that'd charge well, but not discharge (back to photoconductive assist
for the charge removal).
> 
> Some quick Googling suggests that this is indeed a problem in 
> the petroleum industry. In one study they pulled 6 microamps of 
> ground current out of a gas pipe, and that was without intentional 
> charge injection: 
> 
> https://nvlpubs.nist.gov/nistpubs/jres/69C/jresv69Cn4p307_A1b.pdf 
> 
> Everyone who has played with a VdG will understand the desire to 
> get rid of the belt. 6 microamps is well within the ballpark. 
> 
> -- john, KE5FX

Another item, the Kelvin water drop apparatus, gets rid of the
belt in a variant fluid-flow way <https://en.wikipedia.org/wiki/Kelvin_water_dropper>

On Saturday, August 21, 2021 at 1:04:09 PM UTC-7, whit3rd wrote:
> Without particles, the charge might 'track' in any pipe materials it contacts rather 
> than going with the flow. 

True, the petroleum people were apparently finding that corona from the
charged gas or liquid was causing pinhole leaks in the pipe.   But will that 
happen at timescales shorter than the service life of a rubber belt in a VdG?  
Seems unlikely.  

> The alternative would be field-emission points in the liquid flow; 
> that'd charge well, but not discharge (back to photoconductive assist 
> for the charge removal).

Imparting and removing the charge should be simple enough -- I'd just 
envision some steel wool stuffed in the tubing at both ends, where the 
charge/discharge combs would normally be.  As the potential builds, the
back pressure seen by the circulation pump would rise, just like the motor
torque in a conventional static machine.

> Another item, the Kelvin water drop apparatus, gets rid of the 
> belt in a variant fluid-flow way <https://en.wikipedia.org/wiki/Kelvin_water_dropper>

The limitation there seems to be the deflection of the streams of water.  
Closed-loop circulation would be much more effective if it could be 
made workable.  But I think of electrostatics the way most people think of RF...
it never behaves the way I think it will.  Pure FM.

-- john, KE5FX

"John Miles, KE5FX" <jmiles@gmail.com> wrote in
news:9afb478e-474c-4e3e-9dfa-a8060bcf51adn@googlegroups.com: 

> On Saturday, August 21, 2021 at 1:04:09 PM UTC-7, whit3rd wrote:
>> Without particles, the charge might 'track' in any pipe materials
>> it contacts rather than going with the flow. 
> 
> True, the petroleum people were apparently finding that corona
> from the charged gas or liquid was causing pinhole leaks in the
> pipe.   But will that happen at timescales shorter than the
> service life of a rubber belt in a VdG?  Seems unlikely.  
> 
>> The alternative would be field-emission points in the liquid
>> flow; that'd charge well, but not discharge (back to
>> photoconductive assist for the charge removal).
> 
> Imparting and removing the charge should be simple enough -- I'd
> just envision some steel wool stuffed in the tubing at both ends,
> where the charge/discharge combs would normally be.  As the
> potential builds, the back pressure seen by the circulation pump
> would rise, just like the motor torque in a conventional static
> machine. 
> 
>> Another item, the Kelvin water drop apparatus, gets rid of the 
>> belt in a variant fluid-flow way
>> <https://en.wikipedia.org/wiki/Kelvin_water_dropper> 
> 
> The limitation there seems to be the deflection of the streams of
> water.  Closed-loop circulation would be much more effective if it
> could be made workable.  But I think of electrostatics the way
> most people think of RF... it never behaves the way I think it
> will.  Pure FM. 
> 
> -- john, KE5FX
> 

  Maybe add audio as a resonant 'waveguide'.

On Saturday, August 21, 2021 at 3:22:33 PM UTC-7, John Miles, KE5FX wrote:
> On Saturday, August 21, 2021 at 1:04:09 PM UTC-7, whit3rd wrote: 

> > Without particles, the charge might 'track' in any pipe materials it contacts rather 
> > than going with the flow.

> True, the petroleum people were apparently finding that corona from the 
> charged gas or liquid was causing pinhole leaks in the pipe. But will that 
> happen at timescales shorter than the service life of a rubber belt in a VdG? 
> Seems unlikely.

> > The alternative would be field-emission points in the liquid flow; 
> > that'd charge well, but not discharge (back to photoconductive assist 
> > for the charge removal).

> Imparting and removing the charge should be simple enough -- I'd just 
> envision some steel wool stuffed in the tubing at both ends, where the 
> charge/discharge combs would normally be. As the potential builds, the 
> back pressure seen by the circulation pump would rise, just like the motor 
> torque in a conventional static machine.

But, the charge can flow to the edges of the pipe (and the boundary layer near the
surfaces is not flowing as fast as the stream).   Fluorinert won't HOLD much charge,
I'm thinking.   Liquids diffuse, rubber belts don't.

On Thursday, August 19, 2021 at 2:52:22 PM UTC-7, John Miles, KE5FX wrote:
 
> 
> Everyone who has played with a VdG will understand the desire to 
> get rid of the belt. 6 microamps is well within the ballpark. 

I think your 6uA must only involve a couple kilovolts.  If the gas-flow is fighting a 
much stronger e-field,  those measured uA will be orders smaller.

I once tested this and found that "small ions" travel quite fast through air, roughly 30 
mph at a couple tens of KV over several-inch span.  Meaning, your gas-pipe VDG  
would need immense flow-velocities if transporting charged gas against high potential.
The charged molecules must travel backwards slower, than the gas flow forces them
forwards.

But that's for individual charged molecules.  

Instead, some "large ions," meaning nano-soot, or salt crystals, or water-fog, will have 
much larger viscous coupling, and so a much slower gas-flow could push them up into 
a hollow megavolt terminal.  (Or instead just use charged liquid, not charged gas.  
Salad oil isn't too hard to electrify.)

Too bad.  If we could make VDG machines using boxer fans, then you could charge 
yourself up by blowing some wind across sharp needles connected to a cheap 
neg-ion generator, all strapped to your shoes.  (Perhaps it COULD work if you were 
somehow generating a charged water-fog cloud, then blowing that away with a boxer 
fan.)

On Saturday, August 21, 2021 at 9:07:29 PM UTC-7, Bill Beaty wrote:
> ...
> Too bad. If we could make VDG machines using boxer fans, then you could charge 
> yourself up by blowing some wind across sharp needles connected to a cheap 
> neg-ion generator, all strapped to your shoes. (Perhaps it COULD work if you were 
> somehow generating a charged water-fog cloud, then blowing that away with a boxer 
> fan.)
 
Awesome, thanks -- I was hoping you'd debunk the idea before I felt compelled to 
spend time trying it. :)

The boundary-layer issue raised by whit3rd sounds like another showstopper.  
If the charged media doesn't circulate at a uniform velocity, I don't see it working
regardless of the absolute flow rates.

-- john, KE5FX

"John Miles, KE5FX" <jmiles@gmail.com> wrote in
news:734ee1bd-0e03-484a-9ac1-e09cd2aa7b63n@googlegroups.com: 

> On Saturday, August 21, 2021 at 9:07:29 PM UTC-7, Bill Beaty
> wrote: 
>> ...
>> Too bad. If we could make VDG machines using boxer fans, then you
>> could charge yourself up by blowing some wind across sharp
>> needles connected to a cheap neg-ion generator, all strapped to
>> your shoes. (Perhaps it COULD work if you were somehow generating
>> a charged water-fog cloud, then blowing that away with a boxer 
>> fan.)
>  
> Awesome, thanks -- I was hoping you'd debunk the idea before I
> felt compelled to spend time trying it. :)
> 
> The boundary-layer issue raised by whit3rd sounds like another
> showstopper.  If the charged media doesn't circulate at a uniform
> velocity, I don't see it working regardless of the absolute flow
> rates. 
> 
> -- john, KE5FX
> 

  VDG relies on insulator material of a solid nature because the 
electrons reside on the surface of charged insulators.  Remember 
"wiping" them off of a huge TV crt before zapping your sibling(s)?

  Where would the electrons reside on a body of charged dielectric 
fluid?  Much less one that is mobile.

On Sunday, August 22, 2021 at 4:05:22 PM UTC-7, DecadentLinux...@decadence.org wrote:
> Where would the electrons reside on a body of charged dielectric 
> fluid? Much less one that is mobile.

See the .PDF from NIST that I linked to.   If you generate even a few microamps' 
worth of current flow in a moving dielectric medium, you will charge stuff up 
whether you want to or not.  

Given their druthers, the oil & gas industry would really rather not.

-- john, KE5FX

"John Miles, KE5FX" <jmiles@gmail.com> wrote in
news:b7a6cf92-996d-4dd3-b853-fe61c14dd506n@googlegroups.com: 

> On Sunday, August 22, 2021 at 4:05:22 PM UTC-7,
> DecadentLinux...@decadence.org wrote: 
>> Where would the electrons reside on a body of charged dielectric 
>> fluid? Much less one that is mobile.
> 
> See the .PDF from NIST that I linked to.   If you generate even a
> few microamps' worth of current flow in a moving dielectric
> medium, you will charge stuff up whether you want to or not.  
> 
> Given their druthers, the oil & gas industry would really rather
> not. 
> 
> -- john, KE5FX
> 

  A conductor can carry an electrostatic charge.  But ONLY if it is 
insulated from ground or any other node in which to dump it's charge.
In which case it immediately dumps it all.

  An insulator holds its electron charge on its surface and they can 
only be removed by physical contact.

  The triboelectric effect only works on solid surfaces being 
separated from each other.

  So the "charge" can end up "in" the liquid, and then peeled away by 
the conductors it flows against (pipe insides).


  Picking up a piece of paper...  pulling tape off its spool...  
getting a piece of saran wrap out of the box.  All generate ES 
charge.  If the oil and gas industry has a problem, they need to 
incorporate ground straps on all their elevated pipeworks.  Anything 
they have which is held separate from ground can pick up and 
accumulate a charge right out of the air.

  Maybe they should walk up on a worksite with a handheld ESD field 
meter.  Then they could tell if something was carrying a charge or 
not.

  Ours was pretty sensitive.  A person without an ESD smock on can 
make it go nuts simply by aising an arm.

On a sunny day (Mon, 23 Aug 2021 01:03:28 -0000 (UTC)) it happened
DecadentLinuxUserNumeroUno@decadence.org wrote in
<sfus50$1546$1@gioia.aioe.org>:

>getting a piece of saran wrap out of the box.  All generate ES 
>charge.  If the oil and gas industry has a problem, they need to 
>incorporate ground straps on all their elevated pipeworks.  Anything 
>they have which is held separate from ground can pick up and 
>accumulate a charge right out of the air.
>
>  Maybe they should walk up on a worksite with a handheld ESD field 
>meter.  Then they could tell if something was carrying a charge or 
>not.
>
>  Ours was pretty sensitive.  A person without an ESD smock on can 
>make it go nuts simply by aising an arm.

If I walk in these shoes in the supermarket I draw sparks when touching a rack... Painful!
There was  PIN  problem there last week, had to pay cash, some only had cards and could not pay..
Was it me ???
;-)