Can this be done?

[Phil Hobbs]

Dear All:

I have a possibly very interesting instrument application that requires the
application of a very large ac voltage, about 3 kV p-p anywhere between 20
and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small, so I don't want
to use a radar transmitter to drive it. Pulsed operation is fine--duty
cycles of at least 1% are needed, though.

Waveguides and striplines for these frequencies are quite small, which leads
me to worry about corona, rf arcs, and so on.

I don't mind using vacuum if necessary.

Any ideas for less than about $20k in parts?

Thanks,

Phil Hobbs

 

[James Meyer]

On Fri, 01 Apr 2005 19:36:47 -0500, Phil Hobbs <pcdhSpamMeSenseless@us.ibm.com>
wroth:

Dear All:

I have a possibly very interesting instrument application that requires the
application of a very large ac voltage, about 3 kV p-p anywhere between 20
and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small, so I don't want
to use a radar transmitter to drive it. Pulsed operation is fine--duty
cycles of at least 1% are needed, though.

Waveguides and striplines for these frequencies are quite small, which leads
me to worry about corona, rf arcs, and so on.

I don't mind using vacuum if necessary.

Any ideas for less than about $20k in parts?

Thanks,

Phil Hobbs

I *was* going to tell you *exactly* how to do it for about 100 dollars
but I changed my mind when you posted *exactly* the same message *three* times.

Jim

 

[Jim Thompson]

On Sat, 02 Apr 2005 01:15:46 GMT, James Meyer <jmeyer@nowhere.net>
wrote:

On Fri, 01 Apr 2005 19:36:47 -0500, Phil Hobbs <pcdhSpamMeSenseless@us.ibm.com
wroth:

Dear All:

I have a possibly very interesting instrument application that requires the
application of a very large ac voltage, about 3 kV p-p anywhere between 20
and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small, so I don't want
to use a radar transmitter to drive it. Pulsed operation is fine--duty
cycles of at least 1% are needed, though.

Waveguides and striplines for these frequencies are quite small, which leads
me to worry about corona, rf arcs, and so on.

I don't mind using vacuum if necessary.

Any ideas for less than about $20k in parts?

Thanks,

Phil Hobbs

I *was* going to tell you *exactly* how to do it for about 100 dollars
but I changed my mind when you posted *exactly* the same message *three* times.

Jim

Getting crabby in our old age are we ?

Phil is probably cursed with Outhouse Excuse.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[John Larkin]

On Fri, 01 Apr 2005 19:36:47 -0500, Phil Hobbs
<pcdhSpamMeSenseless@us.ibm.com> wrote:

Dear All:

I have a possibly very interesting instrument application that requires the
application of a very large ac voltage, about 3 kV p-p anywhere between 20
and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small, so I don't want
to use a radar transmitter to drive it. Pulsed operation is fine--duty
cycles of at least 1% are needed, though.

Waveguides and striplines for these frequencies are quite small, which leads
me to worry about corona, rf arcs, and so on.

I don't mind using vacuum if necessary.

Any ideas for less than about $20k in parts?

Thanks,

Phil Hobbs

This would have to be inside a cavity or a waveguide; if a signal like
this existed in free space, it would radiate kilowatts. And if it was
a microstrip or stripline, it would probably fry any reasonable
substrate.

The Cebaf (now Jefferson Labs) electron accelerator used
superconductive niobium cavities, each pumped by a fairly small
klystron, to get megavolts/meter fields at something like 3 GHz.

Sounds like magnetron territory to me, not difficult at 1% duty cycle
if you can use a field inside a cavity or waveguide. Who is that
company that has scads of old radar gear and antennas and stuff? Radio
Research or something.

John

 

[Bob]

"James Meyer" <jmeyer@nowhere.net> wrote in message
news:tdsr41ppafu56a9qv8d97vk2j513l2k34g@4ax.com...

On Fri, 01 Apr 2005 19:36:47 -0500, Phil Hobbs
pcdhSpamMeSenseless@us.ibm.com
wroth:

Dear All:

I have a possibly very interesting instrument application that requires
the
application of a very large ac voltage, about 3 kV p-p anywhere between
20
and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small, so I don't
want
to use a radar transmitter to drive it. Pulsed operation is fine--duty
cycles of at least 1% are needed, though.

Waveguides and striplines for these frequencies are quite small, which
leads
me to worry about corona, rf arcs, and so on.

I don't mind using vacuum if necessary.

Any ideas for less than about $20k in parts?

Thanks,

Phil Hobbs

I *was* going to tell you *exactly* how to do it for about 100 dollars
but I changed my mind when you posted *exactly* the same message *three*
times.

Jim

I'll give ya about 200 dollars if you'll tell me, and, I'll only ask once.

Bob

 

[Pooh Bear]

Jim Thompson wrote:

On Sat, 02 Apr 2005 01:15:46 GMT, James Meyer <jmeyer@nowhere.net
wrote:

On Fri, 01 Apr 2005 19:36:47 -0500, Phil Hobbs <pcdhSpamMeSenseless@us.ibm.com
wroth:

Dear All:

I have a possibly very interesting instrument application that requires the
application of a very large ac voltage, about 3 kV p-p anywhere between 20
and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small, so I don't want
to use a radar transmitter to drive it. Pulsed operation is fine--duty
cycles of at least 1% are needed, though.

Waveguides and striplines for these frequencies are quite small, which leads
me to worry about corona, rf arcs, and so on.

I don't mind using vacuum if necessary.

Any ideas for less than about $20k in parts?

Thanks,

Phil Hobbs

I *was* going to tell you *exactly* how to do it for about 100 dollars
but I changed my mind when you posted *exactly* the same message *three* times.

Jim


Getting crabby in our old age are we ?

Phil is probably cursed with Outhouse Excuse.

That's possible but I've had to uneccesarily resend messages ( not using OE ) when
the news server doesn't acknowledge the message sent. Probably happens when the news
server's a bit too busy.

Graham

 

[Phil Hobbs]

Jim Thompson wrote:

On Sat, 02 Apr 2005 01:15:46 GMT, James Meyer <jmeyer@nowhere.net
wrote:


On Fri, 01 Apr 2005 19:36:47 -0500, Phil Hobbs <pcdhSpamMeSenseless@us.ibm.com
wroth:


Dear All:

I have a possibly very interesting instrument application that requires the
application of a very large ac voltage, about 3 kV p-p anywhere between 20
and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small, so I don't want
to use a radar transmitter to drive it. Pulsed operation is fine--duty
cycles of at least 1% are needed, though.

Waveguides and striplines for these frequencies are quite small, which leads
me to worry about corona, rf arcs, and so on.

I don't mind using vacuum if necessary.

Any ideas for less than about $20k in parts?

Thanks,

Phil Hobbs

I *was* going to tell you *exactly* how to do it for about 100 dollars
but I changed my mind when you posted *exactly* the same message *three* times.

Jim



Getting crabby in our old age are we ?

Phil is probably cursed with Outhouse Excuse.

...Jim Thompson

Nah, no such excuse, I use Mozilla--it turned out to be a SMTP relay problem.
I was sending a bcc: to my email account, which the relay complained about,
but silently sent the NG posting along each time.

<abject-humility>
I deeply apologize that I have inexcusably reduced the wisdom-to-noise ratio
of this august NG so much--we almost never get repetitive messages here.
</abject-humility>

Doing this deep in the guts of a magnetron is a good idea, though it might be
hard to get the resulting soft X-rays out of the cavity. (The X-rays are
what I'm interested in--details must be left vague at present.) How big a
voltage swing do you think I can get in, e.g., an evacuated waveguide
resonator before it turns to lava?

Cheers,

Phil Hobbs

 

[keith]

On Fri, 01 Apr 2005 18:35:25 -0700, Jim Thompson wrote:

On Sat, 02 Apr 2005 01:15:46 GMT, James Meyer <jmeyer@nowhere.net
wrote:

On Fri, 01 Apr 2005 19:36:47 -0500, Phil Hobbs <pcdhSpamMeSenseless@us.ibm.com
wroth:

Dear All:

I have a possibly very interesting instrument application that requires the
application of a very large ac voltage, about 3 kV p-p anywhere between 20
and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small, so I don't want
to use a radar transmitter to drive it. Pulsed operation is fine--duty
cycles of at least 1% are needed, though.

Waveguides and striplines for these frequencies are quite small, which leads
me to worry about corona, rf arcs, and so on.

I don't mind using vacuum if necessary.

Any ideas for less than about $20k in parts?

Thanks,

Phil Hobbs

I *was* going to tell you *exactly* how to do it for about 100 dollars
but I changed my mind when you posted *exactly* the same message *three* times.

Jim


Getting crabby in our old age are we ?

Phil is probably cursed with Outhouse Excuse.

Nah, he's not even running WinBlows (OS/2). From his headers:

User-Agent: Mozilla/5.0 (OS/2; U; Warp 4.5; en-US; rv:1.7) Gecko/20040617

--
Keith

 

[Mac]

On Sat, 02 Apr 2005 12:05:23 -0500, Phil Hobbs wrote:

Jim Thompson wrote:
On Sat, 02 Apr 2005 01:15:46 GMT, James Meyer <jmeyer@nowhere.net
wrote:


On Fri, 01 Apr 2005 19:36:47 -0500, Phil Hobbs <pcdhSpamMeSenseless@us.ibm.com
wroth:


Dear All:

I have a possibly very interesting instrument application that requires the
application of a very large ac voltage, about 3 kV p-p anywhere between 20
and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small, so I don't want
to use a radar transmitter to drive it. Pulsed operation is fine--duty
cycles of at least 1% are needed, though.

Waveguides and striplines for these frequencies are quite small, which leads
me to worry about corona, rf arcs, and so on.

I don't mind using vacuum if necessary.

Any ideas for less than about $20k in parts?

Thanks,

Phil Hobbs

I *was* going to tell you *exactly* how to do it for about 100 dollars
but I changed my mind when you posted *exactly* the same message *three* times.

Jim



Getting crabby in our old age are we ?

Phil is probably cursed with Outhouse Excuse.

...Jim Thompson

Nah, no such excuse, I use Mozilla--it turned out to be a SMTP relay problem.
I was sending a bcc: to my email account, which the relay complained about,
but silently sent the NG posting along each time.

abject-humility
I deeply apologize that I have inexcusably reduced the wisdom-to-noise ratio
of this august NG so much--we almost never get repetitive messages here.
/abject-humility

Doing this deep in the guts of a magnetron is a good idea, though it might be
hard to get the resulting soft X-rays out of the cavity. (The X-rays are
what I'm interested in--details must be left vague at present.) How big a
voltage swing do you think I can get in, e.g., an evacuated waveguide
resonator before it turns to lava?

What is a soft X-ray? What is the relationship between these soft X-rays
and the 30 GHz (or whatever) radiation you mentioned in the original post?

I always thought that X-rays were gamma rays with frequencies far beyond
the optical. 30 GHz is far below the optical, obviously. No doubt there is
something I'm missing, possibly due to my ignorance concerning magnetrons.

Cheers,

Phil Hobbs

-- Mac

 

[Phil Hobbs]

bill.sloman@ieee.org wrote:

The 30GHz radiation is probably exciting a plasma, and the X-rays could
come from free electrons encountering positive ions, and dropping into
an orbit close to the nucleus, though they could also arise from
energetic electrons hitting the walls of the chamber.

The volume may be "evacuated" but it isn't empty, and the residual gas
molecules are the source of the plasma. Try searching on "electron
cyclotron resonance" for a bit more detail on what might be going on.

-----------
Bill Sloman, Nijmegen

I'd love to be more specific, but it's a partly-baked idea at
present--it doesn't work, I'll post it so we can all have a good laugh,
and if it does work, you can read about it in Nature. Odds are probably
60% laugh, 20% inconclusive, 20% important. It's a way to make a bright
soft X-ray source fit on a tabletop, instead of requiring a synchrotron.
Early simulations are encouraging, but they rather require this big E
field at high frequency....

So how big a signal can a 30-GHz waveguide (say) take before it starts
arcing in vacuum? Probably it'll be the wall dividing the resonator
from the feeder that will melt first, being thinner. My machine shop
will love being asked for a platinum-plated tungsten waveguide...

Cheers,

Phil Hobbs

 

[John Larkin]

On Mon, 04 Apr 2005 18:41:04 -0400, Phil Hobbs
<pcdh@SpamMeSenseless.us.ibm.com> wrote:

John Larkin wrote:


OK, Pozar page 201. At 10 GHz, a typical air-filled waveguide can
handle about 2.5 MW, e-field peaking around 3e6 v/m. Power capacity is
inverse with frequency, but max e-field stays the same (it's just the
air breakdown limit.) He recommends a 2:1 safety factor from that. One
can improve things by pressurizing with dry gas, or filling with SF6
at atmospheric pressure. The medical xray people who make
microwave-pumped linacs like SF6 so they can make their exit windows
very thin.

Vacuum is interesting; look up the Farnsworth Multipactor effect. It's
caused some serious problems in satellites.

You will do more than publish a paper if this works; the lithography
guys will be all over you. I can introduce you to some folks at Cymer.


John

Brilliant, thanks.

The litho application had crossed our minds. I'm not sure we can go
quite that long in wavelength (litho wants ~100 eV, I think, whereas
we'll probably start out at around 1 keV), but we're certainly going to
try, once we get it working at all.

I'll go calculate some waveguide septa. Tally-ho.

Cheers,

Phil Hobbs

Seen this? Not the same, of course, but weird and interesting.

http://www.amptek.com/coolx.html

"The use of the COOL-X in practical applications will challenge the
user's imagination!"

That's funny!


John

 

[John Larkin]

On Mon, 04 Apr 2005 11:44:08 -0400, Phil Hobbs
<pcdh@SpamMeSenseless.us.ibm.com> wrote:

bill.sloman@ieee.org wrote:


The 30GHz radiation is probably exciting a plasma, and the X-rays could
come from free electrons encountering positive ions, and dropping into
an orbit close to the nucleus, though they could also arise from
energetic electrons hitting the walls of the chamber.

The volume may be "evacuated" but it isn't empty, and the residual gas
molecules are the source of the plasma. Try searching on "electron
cyclotron resonance" for a bit more detail on what might be going on.

-----------
Bill Sloman, Nijmegen


I'd love to be more specific, but it's a partly-baked idea at
present--it doesn't work, I'll post it so we can all have a good laugh,
and if it does work, you can read about it in Nature. Odds are probably
60% laugh, 20% inconclusive, 20% important. It's a way to make a bright
soft X-ray source fit on a tabletop, instead of requiring a synchrotron.
Early simulations are encouraging, but they rather require this big E
field at high frequency....

So how big a signal can a 30-GHz waveguide (say) take before it starts
arcing in vacuum? Probably it'll be the wall dividing the resonator
from the feeder that will melt first, being thinner. My machine shop
will love being asked for a platinum-plated tungsten waveguide...

OK, Pozar page 201. At 10 GHz, a typical air-filled waveguide can
handle about 2.5 MW, e-field peaking around 3e6 v/m. Power capacity is
inverse with frequency, but max e-field stays the same (it's just the
air breakdown limit.) He recommends a 2:1 safety factor from that. One
can improve things by pressurizing with dry gas, or filling with SF6
at atmospheric pressure. The medical xray people who make
microwave-pumped linacs like SF6 so they can make their exit windows
very thin.

Vacuum is interesting; look up the Farnsworth Multipactor effect. It's
caused some serious problems in satellites.

You will do more than publish a paper if this works; the lithography
guys will be all over you. I can introduce you to some folks at Cymer.


John

 

[Don Lancaster]

Phil Hobbs wrote:

Jim Thompson wrote:

On Sat, 02 Apr 2005 01:15:46 GMT, James Meyer <jmeyer@nowhere.net
wrote:


On Fri, 01 Apr 2005 19:36:47 -0500, Phil Hobbs
pcdhSpamMeSenseless@us.ibm.com
wroth:


Dear All:

I have a possibly very interesting instrument application that
requires the application of a very large ac voltage, about 3 kV p-p
anywhere between 20 and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small....


Phil Hobbs

Calculate the current needed to drive ANY amount of capacitance at all
at 50 GHz, and you will find that the power needed is insanely enormous.

UNLESS you can use some sort of precise tuning or matching.

The problem sounds extremely ugly.

--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[John Larkin]

On Sat, 30 Apr 2005 09:53:15 -0700, Don Lancaster <don@tinaja.com>
wrote:

Phil Hobbs wrote:
Jim Thompson wrote:

On Sat, 02 Apr 2005 01:15:46 GMT, James Meyer <jmeyer@nowhere.net
wrote:


On Fri, 01 Apr 2005 19:36:47 -0500, Phil Hobbs
pcdhSpamMeSenseless@us.ibm.com
wroth:


Dear All:

I have a possibly very interesting instrument application that
requires the application of a very large ac voltage, about 3 kV p-p
anywhere between 20 and 50 GHz--it doesn't much matter where.

The actual power dissipated in the instrument is quite small....


Phil Hobbs

Calculate the current needed to drive ANY amount of capacitance at all
at 50 GHz, and you will find that the power needed is insanely enormous.

UNLESS you can use some sort of precise tuning or matching.

The problem sounds extremely ugly.

That's not a huge field inside a waveguide or a resonant cavity.

John