[HN Gopher] National High Magnetic Field Laboratory
___________________________________________________________________
National High Magnetic Field Laboratory
Author : graderjs
Score : 64 points
Date : 2021-06-14 13:26 UTC (9 hours ago)
(HTM) web link (nationalmaglab.org)
(TXT) w3m dump (nationalmaglab.org)
| IgorPartola wrote:
| In college I worked at two labs that did experiments with high
| magnetic fields. The first lab was very cool because the setup
| there used a 50-90 Tesla range and home made magnets along with a
| bank of capacitors they size of about six water coolers to pulse
| the magnets. The magnets themselves would melt pretty quickly but
| not before producing some spectacular results. The samples was
| cooled using a Helium-3 closed loop system that brought the
| temperature down to something like 0.4 K. The professor told me
| that if he put the magnet down with the axis in the vertical
| direction and pulsed it with an iron nail standing under the
| magnet that the nail would reach escape velocity and never come
| back down to earth. I don't know if he ever actually attempted
| that experiment but IIRC the math checked out.
|
| The second lab where I worked used regular Helium (4 K temps) and
| only 5 T magnets to perform slow NMR measurements. We had a
| partnership with the chemistry department and the overall goal of
| the project was to grow a crystal that was able to become opaque
| or transparent by using a magnetic field at room temperatures.
| The idea was that with a crystal like that you could do signal
| switching for fiber optic networks without having to convert the
| signal from optical to electric and back, thus greatly increasing
| network speeds. The effort at the time was 50 years in the making
| and no solution was discovered yet but it was fun to grow my own
| crystals and see how they responded to sweeps of the magnetic
| field, movement in a constant field, and temperature changes. I
| also got to learn Origin C, a peculiar variant of C used by a
| statistical package the lab employed, played with a lot of liquid
| Nitrogen (great for cleaning dusty floors!), programmed a crystal
| growing box/PID controller, and even though I was only an
| undergrad, because it was a small department and lab I got to
| write a thesis and both the physics and chemistry departments
| gathered to see me present it (I was the only physics grad in my
| year despite a dozen the year before and after). The crux of the
| thesis was a new term we called "spin freezing".
|
| But the best part of the whole thing was when I was picking out
| the labs. Every professor had a pitch for why his research was
| the most exciting but the lab I spent the most time with told me
| "when I was your age I also went shopping for labs like you are
| and one of the professors told me he was studying quantum
| magnetism. So I thought to myself 'that sounds like something
| that could impress girls at bars' so I went to work there." That
| reasoning made a lot of sense to me so I signed up for his lab
| right there and then.
| ridgeguy wrote:
| Can you say more about using LN2 to clean dusty floors? Asking
| for a friend.
| myself248 wrote:
| Imagine pouring a bunch of water on the floor that picks up
| and carries the dust some distance, then 2 seconds later the
| water is gone and the dust is deposited in its new location.
|
| It's fantastically effective for carrying crud out from under
| difficult-to-move equipment, to somewhere you can easily
| sweep it up.
| IgorPartola wrote:
| This. It carries the dust to the walls and then you just
| sweep the edges. Just sweep it on the floor and watch it
| work.
| mrfusion wrote:
| We should pursue this as a launch system. Anything not affected
| by high G's could work. Raw materials, maybe fuel.
| gene-h wrote:
| It's not a very ideal launch system. Not only must your
| payload contend with high accelerations, but also a huge
| pulsed magnetic field. This will make launching electronics
| more difficult, because they will be exposed to a large
| electromagnetic pulse.
| dokem wrote:
| Rail guns are under active development. Also, escape velocity
| is not practical in that is doesn't account for atmosphere.
| IgorPartola wrote:
| That and acceleration at launch will kill most cargo.
| bananabreakfast wrote:
| https://en.wikipedia.org/wiki/Project_HARP
| jessriedel wrote:
| > Every professor had a pitch for why his research was the most
| exciting but the lab I spent the most time with told me "when I
| was your age I also went shopping for labs like you are and one
| of the professors told me he was studying quantum magnetism. So
| I thought to myself 'that sounds like something that could
| impress girls at bars' so I went to work there." That reasoning
| made a lot of sense to me so I signed up for his lab right
| there and then.
|
| This is fine for undergraduate research assistants since it's
| unreasonable to expect an undergrad to be able to judge a
| research program on its merits and you're expected to switch
| labs in the future anyway. It's much more concerning that
| graduate students usually select research labs without being
| able to assess the basic scientific case on the merits. The
| issue is that once you pick your PhD topic, it's logistically
| very hard to change research focus more than slightly for the
| rest of your career. So research programs can get perpetuated
| across multiple generations even if no well-informed student
| would start down that path.
| SiempreViernes wrote:
| Though it's very important to get a supervisor you can
| collaborate with, especially for your mental health, so
| choosing mainly based on personal chemistry is a valid
| strategy.
| graderjs wrote:
| This is a great story, thanks for sharing. I'm a chemistry
| graduate and also had fun sweeping the dusty chem lab floor
| with liquid n2! ;P ;) xx
| egfx wrote:
| > _The professor told me that if he put the magnet down with
| the axis in the vertical direction and pulsed it with an iron
| nail standing under the magnet that the nail would reach escape
| velocity and never come back down to earth_
|
| Hmm that sounds suspiciously like the descriptions of the
| systems that are rumored to operate and power UFO's. Research
| "electrogravitics".
| egfx wrote:
| To all those downvoting. Do your due diligence first like I
| did ;)
| jodrellblank wrote:
| Coil up some wire and run electricity through it, you get a
| magnetic field which can pull magnetic materials. That's an
| electromagnet, e.g. used in door locking systems, and
| lifting cars into car crushers. Instead of pulling on a
| car, fix some magnetic material to an axle and a ring of
| coils around it, the magnetic pulls make the axle turn, you
| have an electric motor.
|
| Have some freely moving magnetic material, and unroll the
| motor into a line of coils, and you can make a linear motor
| as used in a maglev train. Make the electric current pulses
| powerful enough, and the thing is fired away very fast,
| your linear motor becomes a rail gun.
|
| Make a huge pulse and make the thing small and light, and
| it could go fast enough to reach escape velocity from one
| coil. Handwavy estimates: An 8d nail weighs around 5
| grams[1], it takes 28kWh to get 1kg past escape
| velocity[2], so about 150Wh into the nail might do it. Pump
| about 2 laptop batteries worth of energy into accelerating
| the nail between the moment it picks up off the ground, and
| the moment it exits the top of the coil travelling at
| several kilometers per sec - that's going to need a big
| setup with supercooling and high power capacitors because
| the time window is so short, not because it's using secret
| alien technology.
|
| It doesn't sound "suspiciously like gravity manipulation"
| at all?
|
| [1] at ~100 8d nails to the pound, and ~450grams to the
| pound, 1/100th of 450 makes 4.5grams, rounded up: https://w
| ww.treeisland.com/sites/default/files/documents/bro...
|
| [2] https://space.stackexchange.com/questions/4330/how-
| much-ener...
| egfx wrote:
| >It doesn't sound "suspiciously like gravity
| manipulation" at all?
|
| Try adding some rotary effects and then it may. You gotta
| think outside the globe.
| AnimalMuppet wrote:
| Could you, like, give some actual detail, instead of
| making us try to guess what you have in mind? Because
| we're bored of that game...
| egfx wrote:
| sure not a problem. Parse through this document : https:/
| /patentimages.storage.googleapis.com/0e/5e/e0/eb08a31...
| AnimalMuppet wrote:
| Interesting. Granted in December 2005. So in the
| intervening 15 1/2 years, has someone shown a working
| device? Can you point me to documentation of that?
| bloak wrote:
| > the nail would reach escape velocity and never come back down
| to earth
|
| See https://en.wikipedia.org/wiki/Impact_depth
|
| I am not a physicist, but iron is about 6500 times denser than
| air so that suggests that a 5 cm nail would reach a height of
| very roughly about 300 metres, assuming you fired it upwards
| with sufficient speed, it remained parallel to the direction of
| flight, and it didn't melt or burn.
|
| You should definitely allow more space that that if you're
| thinking about filming the experiment from a helicopter over
| your magnet lab, but I would guess that even Nine Inch Nails
| wouldn't be hitting any satellites.
|
| EDIT: OK, that impact depth formula is only applicable to
| projectiles travelling faster than the speed of sound in the
| medium, which is about 300 m/s. But without air resistance an
| object fired upwards at 300 m/s reaches a height of about 4500
| metres! There's a big gap between those two rough
| approximations, so if someone wants a more accurate answer I
| suppose they will just have to look up the actual formulae for
| actual air resistance.
| bananabreakfast wrote:
| Interesting point. Although, a 5cm nail is tiny, that's like
| what you'd use to hang a picture on the wall.
|
| A real carpenter's nail is what I was picturing and that's
| more like 10-15cm which 2-3x's your impact depth (which is
| still only ~1km).
|
| So I think if anything, your point is basically proof that a
| nail or any traditional gauss gun projectile would absolutely
| ablate into gas immediately when fired at the hypersonic
| speed of orbital escape velocity.
| jjk166 wrote:
| Yeah, that's why the "rod's from god" idea for an orbit to
| ground kinetic weapon (which is the same problem just in
| reverse) used tungsten rods the size of telephone poles,
| and even those would slow down by 5 km/s as they pass
| through the atmosphere.
| schrodingersCat wrote:
| I'm a little confused why the NHMFL home page ended up in my
| hacker news RSS feed, but I received my PhD here and thus feel
| obligated to comment and upvote...
| anon_tor_12345 wrote:
| i mean nhmfl isn't a degree granting institution so i think you
| mean you got your phd at fsu
| Workaccount2 wrote:
| Seize the opportunity to talk about what you did there!
| Splendor wrote:
| Me too. I did notice another story for the same domain on
| today's front page of HN.
|
| https://news.ycombinator.com/item?id=27502233
| hex1848 wrote:
| My first development gig in high school was at the NHMFL working
| with the photo microscopy guys on various projects. It was a
| great experience that got my development career rolling. This was
| the mid/late 90's. We went from developing hyper card stacks to
| OSHA training educational tools and testing in HTML/perl. Good
| times.
___________________________________________________________________
(page generated 2021-06-14 23:01 UTC)