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Coil inside of plasma tube

J

James Baker

Jan 1, 1970
0
We are intending to have a gas-filled tube made up for experimental
purposes that has a coil sealed inside. The gas will be ionized with
about 250VAC, via a rod down the center and a conformal external
plate. The coil just sits inside, fed by a separate low voltage, high
current signal.

Of course, we do not want the latter to be shorted by the plasma, so
we are considering to use kynar insulated wire for the entire winding
which will be brought out through the glass during manufacture

Does anyone here see any problems on a practical or fabrication level
with this?

Jim baker
 
J

Jamie

Jan 1, 1970
0
James said:
We are intending to have a gas-filled tube made up for experimental
purposes that has a coil sealed inside. The gas will be ionized with
about 250VAC, via a rod down the center and a conformal external
plate. The coil just sits inside, fed by a separate low voltage, high
current signal.

Of course, we do not want the latter to be shorted by the plasma, so
we are considering to use kynar insulated wire for the entire winding
which will be brought out through the glass during manufacture

Does anyone here see any problems on a practical or fabrication level
with this?

Jim baker
I assume the leads will be molded/passing through the glass envelope?

How do you plan on getting the Kynar wire molded in this with out it
melting? Kynar at extrusion is ~ 550F to make it soft enough to apply
FEP (teflon) is around 750F.

How much heat is going to be on this wire inside?

Kynar is not very adhesive so using a ported hole with sealer may be
short lived before the gas leaks. I suppose chemicals have come a long
ways these days, it may not be the case any more.

This is all about construction not operation concerns.
Jamie
 
S

Spehro Pefhany

Jan 1, 1970
0
We are intending to have a gas-filled tube made up for experimental
purposes that has a coil sealed inside. The gas will be ionized with
about 250VAC, via a rod down the center and a conformal external
plate. The coil just sits inside, fed by a separate low voltage, high
current signal.

Of course, we do not want the latter to be shorted by the plasma, so
we are considering to use kynar insulated wire for the entire winding
which will be brought out through the glass during manufacture

Does anyone here see any problems on a practical or fabrication level
with this?

Jim baker

Hmm.. can you test the wire insulation under simulated conditions in a
bell jar?


Best regards,
Spehro Pefhany
 
J

James Baker

Jan 1, 1970
0
It appears that you actually don't want the coil to be in contact with the
plasma. Only to create a magnetic field inside of the assembly. If so, can
you locate the coil just outside the plasma tube and adjust the coil
current so as to generate the requisite B field inside the slightly larger
area?

For this exp the plasma needs to be physically both inside and outside
of the coil. IOW the coil is air wound before insertion.

James
 
J

James Baker

Jan 1, 1970
0
How do you plan on getting the Kynar wire molded in this with out it
melting? Kynar at extrusion is ~ 550F to make it soft enough to apply
FEP (teflon) is around 750F.

Good point. Glass melts beginning at 2500 F. Is there any wire
insulation that will withstand this?
How much heat is going to be on this wire inside?

The coil will be placed in the center section of a tube and the ends
sealed. It can be as far away from the torch as required. The problem
is getting the wire OUT.
Kynar is not very adhesive so using a ported hole with sealer may be
short lived before the gas leaks. I suppose chemicals have come a long
ways these days, it may not be the case any more.

Does anyone have anything further on this ported hole approach?

James
 
J

Jeffery Tomas

Jan 1, 1970
0
"James Baker" wrote in message news:[email protected]...
For this exp the plasma needs to be physically both inside and outside
of the coil. IOW the coil is air wound before insertion.

James

What if you essentially coat the wire with glass instead?

Something like a klein bottle? This would get you the separation of having
the coil outside but allow plasma to be inside and out. It should not be
difficult to make. You are effectively just coating the wire with glass.

It may be hard to visualize but think of having a glass coil(like some of
the light bulbs you see) that is inside the vessel.

The added benefit is that you do not have to worry about leakage at the
ends. You can also run multiple conductors through the coil if needed.

--
 
S

Spehro Pefhany

Jan 1, 1970
0
Good point. Glass melts beginning at 2500 F. Is there any wire
insulation that will withstand this?

Close (and there are lower temperature glasses). Mineral insulated
(MI). It's used in some process control applications because it will
still function in extreme conditions such as a refinery fire. The
outer shell could be something like Inconel.

http://www.tycothermal.com/assets/Europe/English/Document/Datasheets/2895/DOC-389_R10_HIQ.pdf
http://www.hightempmetals.com/techdata/hitempInconel617data.php

The coil will be placed in the center section of a tube and the ends
sealed. It can be as far away from the torch as required. The problem
is getting the wire OUT.


Does anyone have anything further on this ported hole approach?

James


Best regards,
Spehro Pefhany
 
S

Spehro Pefhany

Jan 1, 1970
0
"James Baker" wrote in message news:[email protected]...

What if you essentially coat the wire with glass instead?

Something like a klein bottle? This would get you the separation of having
the coil outside but allow plasma to be inside and out. It should not be
difficult to make. You are effectively just coating the wire with glass.

It may be hard to visualize but think of having a glass coil(like some of
the light bulbs you see) that is inside the vessel.

You mean like this?

http://www.glasscolabs.com/dimroth-condenser-for-soxhlet-72.html

The added benefit is that you do not have to worry about leakage at the
ends. You can also run multiple conductors through the coil if needed.

--


Best regards,
Spehro Pefhany
 
M

Martin Riddle

Jan 1, 1970
0
James Baker said:
We are intending to have a gas-filled tube made up for experimental
purposes that has a coil sealed inside. The gas will be ionized with
about 250VAC, via a rod down the center and a conformal external
plate. The coil just sits inside, fed by a separate low voltage, high
current signal.

Of course, we do not want the latter to be shorted by the plasma, so
we are considering to use kynar insulated wire for the entire winding
which will be brought out through the glass during manufacture

Does anyone here see any problems on a practical or fabrication level
with this?

Jim baker

Most tubes use steel(nickel plated) wire annealed to the glass to make
the outside world connections.
And I'm sure most tube guys will agree.

And yes the Kynar would melt.

Why don't you check with the Tube manufacturers? Like Xray tubes and
such.
It's a craft, and they would know best how to organize the inside such
that it would work.

You might even be able to put a tube within a tube to isolate the
winding.

Cheers
 
J

Jeffery Tomas

Jan 1, 1970
0
"Spehro Pefhany" wrote in message

Yeah!

You do not need something as fancy,

cross section,

|----------------|
| |
| ___ ___ |
| |+| |+| |
| |+| |+| |
| |+| |+| |
| |+| |+| |
| |+| |+| |
---- ---- ----



would work just as well. Basically like an E-Core transformer but it is
cylindrical. (the + being the coil)

This would be even easier to make and probably do a better job.
 
J

Jamie

Jan 1, 1970
0
Jeffery said:
"James Baker" wrote in message


What if you essentially coat the wire with glass instead?

Something like a klein bottle? This would get you the separation of
having the coil outside but allow plasma to be inside and out. It should
not be difficult to make. You are effectively just coating the wire with
glass.

It may be hard to visualize but think of having a glass coil(like some
of the light bulbs you see) that is inside the vessel.

The added benefit is that you do not have to worry about leakage at the
ends. You can also run multiple conductors through the coil if needed.

--
You know what ,that's a good idea however, I think the thermo movements
may crack the glass around it.

A double lined tube with only the center tube having the gas and seal
is what's needed from what I can see. standard practices how tubes are
assembled can be used here. Otherwise, since he wants it insulated, why
would it need to be directly inside? Unless he is looking for a faster
change ?

The whole unit can be made to plug into an octal base socket for example.

There is a process I've seen that I really don't understand why it
was done that way. They made a coil inside a tube from miniature Fep
coax. attached the centers to the feed through pins in the base of the
glass. Filled the base of the glass with a sealer that covered the pins
up to the center conductors insulation and over a bit, there by keeping
it sealed from what ever they were putting in the rest of it. The shield
was then pushed back down to the bottom after the first set harden and
then a thin coat of the same sealer was applied to attach the braid to
base with out it shorting to the center. I assume they may have done
this to keep the shield from sliding around.. I didn't see what was in
the rest of the tube.


Jamie
 
C

Cydrome Leader

Jan 1, 1970
0
James Baker said:
We are intending to have a gas-filled tube made up for experimental
purposes that has a coil sealed inside. The gas will be ionized with
about 250VAC, via a rod down the center and a conformal external
plate. The coil just sits inside, fed by a separate low voltage, high
current signal.

Of course, we do not want the latter to be shorted by the plasma, so
we are considering to use kynar insulated wire for the entire winding
which will be brought out through the glass during manufacture

Does anyone here see any problems on a practical or fabrication level
with this?

What's the size of the tube and coil?
 
F

Fred Abse

Jan 1, 1970
0
Most tubes use steel(nickel plated) wire annealed to the glass to make
the outside world connections.

The wire is actually an nickel-cobalt-iron alloy , with a controlled
coefficient of expansion to match that of the glass.

http://en.wikipedia.org/wiki/Kovar

That is what made all-glass tubes with lead-in wires thick enough to be
used as standalone pins possible.
 
J

josephkk

Jan 1, 1970
0
We are intending to have a gas-filled tube made up for experimental
purposes that has a coil sealed inside. The gas will be ionized with
about 250VAC, via a rod down the center and a conformal external
plate. The coil just sits inside, fed by a separate low voltage, high
current signal.

Of course, we do not want the latter to be shorted by the plasma, so
we are considering to use kynar insulated wire for the entire winding
which will be brought out through the glass during manufacture

Does anyone here see any problems on a practical or fabrication level
with this?

Jim baker

That sounds awfully close to what is currently called an "Induction Lamp".
You might compare your construction to theirs.

?-)
 
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