Field research

[unixronin]

Magnetic field, that is.  "Black gold, Texas ..."  No, want a minute, that's not right.

The ATLAS Barrel Toroid, the world's largest superconducting magnet, has been successfully powered up and tested at CERN's Large Hadron Collider.  After being cooled down to 4 Kelvin over a six-week period, it was gradually powered up over the course of about two months, reaching a peak current of 21,000 amps.

Yeah.  But if that number, which is 500 amps over "nominal field", makes your eyebrows rise, try this one for size:  At that current, the stored magnetic energy in the field was 1.1 GJ.  After being powered off, it took ten days for the field to decay, raising the temperature of the magnet from 4 Kelvin to 53 Kelvin.

The article doesn't state the actual field strength.  But that's one holy hell of a magnetic field.

(Click the thumbnail for some serious "Ooh!  SHINY!")

(Link from mrmeval)

Comments

[smandal.livejournal.com]

The average magnetic field strength is easily calculated:

energy density U = B^2 / 2 \mu_0 = E / V = E / (\pi d^2/4 * l)

B = sqrt(8 E \mu_0 / pi d^2 l)

= 2.3 Tesla

The actual magnetic field strength varies from 1 to 4 Tesla.

For reference, 1.1 GJ is about the same as 250 kg of TNT; this is the yield of a suitcase nuke or an Exocet missile.

Here's a cool brochure in PDF (http://cern.ch/atlas-magnet/info/project/ATLAS_Magnet_Leaflet.pdf).

[unixronin.livejournal.com]

The average magnetic field strength is easily calculated:

energy density U = B^2 / 2 \mu_0 = E / V = E / (\pi d^2/4 * l)

B = sqrt(8 E \mu_0 / pi d^2 l)

= 2.3 Tesla

That's easy for you to say. :) I personally freely admit I don't know how to calculate it.

[ithildae.livejournal.com]

The equations and explanation are in any first year physics book, second half. Given some motivation and the text, you would have no problem with it.

[unixronin.livejournal.com]

I don't doubt knowing where to find the equations would be half the battle. :) I'm just so rusty on my physics ..... :(

[dafydd.livejournal.com]

The installation of one of the Atlas coils has been a topic of one of the extreme engineering shows wandering across The History Channel over the last week.

[danjite.livejournal.com]

How do y'all reckon the operation of said device effected computer use and within what radius?

[unixronin.livejournal.com]

I would expect the field to be entirely, or almost entirely, contained within the barrel.  One thing is for sure, though, the Hall effect on any semiconductor in the field would be significant. See the Wikipedia page on the tesla as a unit of magnetic field strength (http://en.wikipedia.org/wiki/Tesla_%28unit%29) for some comparative examples.

It's not that the ATLAS barrel actually generates a staggeringly intense field. (From the above cited page, the strongest continuous field generated to date is in the 85-100 T range.) You can come close with a set of neodymium-iron-boron rare-earth magnets for a few dollars. It's that for a field of that strength, it's so damned BIG.

[smandal.livejournal.com]

The field leakage is is only 0.1 T at the surface of the barrel. Obviously any distance away it becomes miniscule.

[tww1fa]

Sounds like an awful lot of trouble just to research a Jean-Michel Jarre album...

[unixronin.livejournal.com]

Clearly he has at least one album out of which I am unaware. (I have Oxygene and Equinoxe.)

[callahanshappy.livejournal.com]

Chants Magnetiques from 1981.

[unixronin.livejournal.com]

Right. Right. I've seen that. I just forgot it........