WB-8 Coming

[MSimon]

David,

I might use an analog output with a switching supply power preprocessor. It all depends. And yes you can get more than 16 bits with digital techniques as you suggest. It all depends on how much ripple you can tolerate and where in the band the ripple is vs the output. The technique is called oversampling.

With 18 and 24 bit D to As at reasonable prices now common why bother for a device which will be produced in the thousands until the next improved version?

[choff]

I say build on what you have and what you're already familiar with. If any 2 of WB6's magnets are still operational then add them to WB7.1 to form an 8 sided magrid. This appeals to the scrounge in me. Get the results you need with the minimum departure from the known. You would still have plenty of money left over for the all new machine and a backup set of data for delivery to the USN.

[MSimon]

I say build on what you have and what you're already familiar with. If any 2 of WB6's magnets are still operational then add them to WB7.1 to form an 8 sided magrid. This appeals to the scrounge in me. Get the results you need with the minimum departure from the known. You would still have plenty of money left over for the all new machine and a backup set of data for delivery to the USN.

That is not a bad idea if the tits can be scraped off and rewelded with the current carrying conductors going through the new tits. Tit angles and position will have to change too.

And don't forget to buy 33% more batteries to keep the current up.

BTW tit is a technical term.

[ravingdave]

David,

I might use an analog output with a switching supply power preprocessor. It all depends. And yes you can get more than 16 bits with digital techniques as you suggest. It all depends on how much ripple you can tolerate and where in the band the ripple is vs the output. The technique is called oversampling.

With 18 and 24 bit D to As at reasonable prices now common why bother for a device which will be produced in the thousands until the next improved version?

I see what you mean. Yeah, that makes perfect sense.



David

[choff]

They might be able to work out a TV advertising deal with a battery company. Think of the catch line, "When the US Navy needed batteries to test their fusion reactor, they chose ---." Any Ad exec would just love selling it to a battery maker, and EMC2 could profit too!

[ravingdave]

I say build on what you have and what you're already familiar with. If any 2 of WB6's magnets are still operational then add them to WB7.1 to form an 8 sided magrid. This appeals to the scrounge in me. Get the results you need with the minimum departure from the known. You would still have plenty of money left over for the all new machine and a backup set of data for delivery to the USN.

That is not a bad idea if the tits can be scraped off and rewelded with the current carrying conductors going through the new tits. Tit angles and position will have to change too.

And don't forget to buy 33% more batteries to keep the current up.

BTW tit is a technical term.

So is "Nipple" if you are a plumber or electrician. In 1941, the modification to the British Spitfire carburetor (to prevent stalling during negative Gs) was referred to as "Miss Shilling's orifice" after the inventor Beatrice Shilling. The old army caps were referred to as c*nt caps. Electrical Connectors come in "Male" and "Female" versions.

While we're on the subject, Stephen Fry and Hugh Laurie used to do a show called "A bit of Fry and Laurie", and in one episode Hugh Laurie plays the role of a parts salesman and Stephen Fry plays the part of a repair man asking for parts. They run the gamut of nasty sounding parts names and how they are employed in various repairs. Twas one of the funnier episodes.

Edit: Found the Link !

http://www.youtube.com/watch?v=VcnbfHGPxT0


One more thing on the Superconducting Magnets. The PDF I read mentioned that if one of the magnets move relative to the other even a slight amount, it will instantly quench.

Charging up six of these in conjunction with each other promises to be a fairly dicey problem.



David

[MSimon]

The PDF I read mentioned that if one of the magnets move relative to the other even a slight amount, it will instantly quench.

That may have to do with material and construction methods. I'd love it if you would do a search and find the report. I have done some noodling around and couldn't find anything.

[D Tibbets]

I say build on what you have and what you're already familiar with. If any 2 of WB6's magnets are still operational then add them to WB7.1 to form an 8 sided magrid. This appeals to the scrounge in me. Get the results you need with the minimum departure from the known. You would still have plenty of money left over for the all new machine and a backup set of data for delivery to the USN.

I don't know how accurate the information was, but at one time WB 7 was described as being 35 CM wide -versus the 30 cm width of WB 6. If true, the magnets could not be mixed. Also WB 6 had 200 wire turns, how many does WB 7 have?

Dan Tibbets

[ravingdave]

The PDF I read mentioned that if one of the magnets move relative to the other even a slight amount, it will instantly quench.

That may have to do with material and construction methods. I'd love it if you would do a search and find the report. I have done some noodling around and couldn't find anything.

I thought I had saved the link somewhere, but i've looked on three different machines i've used in the likely time frame and I can't find it. After a lot of searching i've noticed that I can't find sites that i've browsed before, so the document may no longer be available. If I remember correctly the document was a service manual or guide to charging and quenching superconducting magnets for scientific and medical purposes.

In any case I did find this:

Premature quenching can also occur if the large forces between coil sections result in the motion of one coil with respect to another. This is most likely to occur in magnets having coils that are wound in opposition. Such coils are used in bucking coil magnets and magnets for nuclear demagnetization where a low field region is required close to a high field region.

http://www.americanmagnetics.com/tutorial/magnetp.html


I'll look around some more tomorrow.


David

[choff]

Unless the 35cm was outer diameter and the 30 cm inner.

[MSimon]

SC Mag. PWR supply.

Looks like a linear job. Output noise is line related.

http://www.lakeshore.com/pdf_files/inst ... _625_l.pdf

Magnet Safety.

http://ccc.chem.pitt.edu/wipf/Former%20 ... Safety.pdf

Refurbished MRI units India:

http://medirayhealthcare.tradeindia.com ... orter.html

They currently have a 1.5 T unit for $400,000

MRI Operator manual:

http://www.mayoclinicmedicaldevices.com ... nglish.pdf

Used MRI - Texas

http://crestimaging.com/imaging_equipment.php

MRI Cary, Illinois - about 60 road miles from me

http://www.bmimed.com/pages/mri_equipment/17.php

MRI - New York

http://www.monarchmedical.com/newmonarchmri.asp

That should keep you busy. Prices for used MRIs of 1.5 T are in the $400K to $500K range.

I wonder if you can get the magnet set only?

[MSimon]

MRI services Huntley, Illinois about 30 or 40 miles from me:

http://www.genesismagnet.com/magnet_services.html

Varian, UK

http://www.varianinc.com/cgi-bin/nav?pr ... KNPMOQNKFQ

Wire, cable, magnets

http://www.supercon-wire.com/newsandevents_main.html

Magnet Design Software

http://www.magnetica.fr/1-magnet-design ... agnet.html

A 3T machine available Dec 2008 Florida

http://www.alibaba.com/product-tp/10383 ... T_MRI.html

And the number 2 item on the google search for "mri superconducting magnet manufacturer" -->

http://iecfusiontech.blogspot.com/2008/ ... oling.html

Heh. Anyone want to start a business? I have the Google ranking.

[Josh Cryer]

How do you adapt the MRI magnets to Polywell?

[KitemanSA]

How do you adapt the MRI magnets to Polywell?

MSimon, in another topic, provided a cut-away graphic of a particular MRI machine. The main superconducting magnet in that MRI machine showed 6 segments, each of almost square minor cross section. He opined that the segments can be seperated and placed into their own casings and used just like the toroidal magnet of WB6/7 only bigger, superconducting, and continuous. It is a great idea if the magnet segments can indeed be seperated. I hope they can.

He is now looking harder and harder for cheap (i.e. used) machines that can be canabalized for the main magnet segments. I wish him good fortune.

[Nik]

From long, long ago, when 'Scientific American' was worth reading, I remember an article on 'very high magnetic fields'. IIRC, they ran gamut of cunning field-poles for 'ordinary' electromagnets, pulsed coils, explosive compression and SC systems.

Problem with SC was, as this thread states, charging the ruddy thing up. One trick seemed to be ramping in an external supply then short-circuiting the link. Fuse blows in supply, of course, of course, but current continues to circulate in SC.

Another, elegantly but improbably, used an integral homopolar generator. I *think* it was a Philips (Netherland) design, it had that grin.

Effectively, the lead SC coil was connected betwen axis and rim of a lead SC disk. One pole of a magnet was 'stirred' around the disk plane, with the work generating more circulating current at each pass. To reduce the current, the magnet was allowed to unwind, 'stirred' in opposite direction as a motor...

I never saw the actual rather than conceptual configuration, and the technology soon moved beyond such electro-mechanical clunkiness.

But, as an alternative to horrendously expensive power supplies...