Fastest rotating man-made object created (600 million RPM!)

[Jamie M]

Hi,

A 4um diameter sphere of calcium carbonate was optically levitated
by a laser, and the laser polarization was used to spin the
sphere up to 600 million RPM, at which point it disintegrated!

http://phys.org/news/2013-08-fastest-rotating-man-made.html

I guess it won't be long until someone will do this with diamonds,
as they are being optically levitated as well:

http://phys.org/news/2013-08-optically-levitate-nanoscale-diamond-video.html

How does the laser polarization work to spin up the sphere?

cheers,
Jamie

 

[RobertMacy]

Circularly polarized light carries angular momentum (not OAM, photon
spin).

A 10 MHz rotation rate is going some. It's interesting that the surface
velocity was omega R ~= 125 m/s at failure, when the centripetal
acceleration was omega**2 R ~=800 million gees.

Cheers

Phil Hobbs

what is the energy?

 

[Phil Hobbs]

what is the energy?

Not very big. The rotational KE is 1/2 I * omega**2, where I is the
moment of inertia. For a uniform sphere,

V = 4/3 pi R**2
I = 2/5 M R**2 = 8/15 pi R**5 rho .

For calcite, rho = 2.7e3 kg/m**3, so

KE = 4/15 pi**3 (10 MHz)**2 (2 um)**5 2.7e3 ~= 70 pJ.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Phil Hobbs]

Not very big. The rotational KE is 1/2 I * omega**2, where I is the
moment of inertia. For a uniform sphere,

V = 4/3 pi R**2
I = 2/5 M R**2 = 8/15 pi R**5 rho .

For calcite, rho = 2.7e3 kg/m**3, so

KE = 4/15 pi**3 (10 MHz)**2 (2 um)**5 2.7e3 ~= 70 pJ.

Cheers

Phil Hobbs

Volume is R**3 of course. I think the rest is right.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Bill Sloman]

NMR samples, especially solids, are spun at speeds up to 70 KHz. They
mostly use air motors.

Modified dentist's air drills? Dentists drills themselves don't spin nearly fast enough (500Hz), but it's a nice compact package designed to go into a confined space ...

 

[Jamie M]

Modified dentist's air drills? Dentists drills themselves don't spin nearly fast enough (500Hz),

but it's a nice compact package designed to go into a confined space ...
How fast can you spin a strong diamond, or carbyne even stronger apparently:

http://phys.org/news/2013-08-carbyne-stronger-material.html

before it structurally fails?

cheers,
Jamie

 

[Carl Ijames]

A 1 GHz proton nmr magnet is 23.5 T, not 250.

-----
Regards,
Carl Ijames
"John Larkin" wrote in message

Yes, that's exactly what these are, solid NMR samples.
I sure haven't heard of 70K RPS, and since we have some pretty strong
magnets, I doubt anyone is doing 70K RPS. The spin speed scales
with the strength of the superconducting magnet field. I think
our strongest one is almost 10 T, and few go above that.

Jon

There are some 1 GHz magnets around, 250T. They have a spiral staircase
wrapped
around them so you can get to the top to load samples. A couple of megabucks
or
some such.

Wiki mentioned the 70 KHz value

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

I think my customers usually run maybe a tenth of that.

Whose stuff do you use? Varian? Bruker?


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

 

[Jeff Layman]

Circularly polarized light carries angular momentum (not OAM, photon spin).

A 10 MHz rotation rate is going some. It's interesting that the surface
velocity was omega R ~= 125 m/s at failure, when the centripetal
acceleration was omega**2 R ~=800 million gees.

Cheers

Phil Hobbs

Any idea what the tensile strength of calcite is? I note the comment
from one of the investigators:
"The rotation rate is so fast that the angular acceleration at the
sphere surface is 1 billion times that of gravity on the Earth surface–
it's amazing that the centrifugal forces do not cause the sphere to
disintegrate!".

Somewhat OT, but around 50 years ago I remember looking through a
textbook of electronic circuits, published in the mid-50s. IIRC, one
was used to spin a small aluminium rod, I think about 10 mm long and 5
mm across (hexagonal cross-section), to 5 million rpm in a vacuum. The
rod was levitated above a coil by a magnetic field, and another coil
applied a spin to it. It's many years ago, so my memory may be
incorrect, but I think it took at least 2 hours for the rod to reach
maximum speed. Is that possible, or is my imagination working overtime?!

 

[RobertMacy]

Sounds reasonable. The torque you can get that way isn't that big,
unless you have a lot of iron (as in a squirrel cage motor).

Small single crystals can be quite a bit stronger than bulk material,
especially if they're prepared so as to have a very smooth surface.
(It's the largest crack that limits the ultimate strength, just like the
proverbial weakest link in a chain.)

Cheers

Phil Hobbs

Interesting that an 'aluminium' rod was levitated by a coil.

or, even iron, makes one wonder how much 'drag' is then exerted upon the
rotation by the earth's field. Maybe gone faster?

 

[Tauno Voipio]

Interesting that an 'aluminium' rod was levitated by a coil.

Good conductor and not too heavy, eddies swirl happily inside
to create a response to the alternating magnetic field.

 

[Phil Hobbs]

Sounds reasonable. The torque you can get that way isn't that big,
unless you have a lot of iron (as in a squirrel cage motor).

Small single crystals can be quite a bit stronger than bulk material,
especially if they're prepared so as to have a very smooth surface.
(It's the largest crack that limits the ultimate strength, just like the
proverbial weakest link in a chain.)

I think I vaguely remember a Popular Electronics or Electronics
Illustrated article from the '60s about doing magnetic levitation and
spinning using toobs--it was called something imaginative like "Li'l Atlas".

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058

hobbs at electrooptical dot net
http://electrooptical.net

 

[Jamie M]

Volume is R**3 of course. I think the rest is right.

Cheers

Phil Hobbs

Hi,

Does the light provide a constant torque as the objects rotation rate is
increasing? I guess the torque will decrease until the object was
rotating to match the circular polarization "spiral" of the EM field,
based on the speed of propagation of light through the object too.
So the object will accelerate slower as it speeds up if the torque
isn't constant. Also I wonder about the torque exerted on the object
in relation to the frequency of circularly polarized light used? As
long as the object is longer than one complete 360 degree polarization
cycle, then if the frequency of light is increased would the torque
remain the same or possibly increase? If the torque exerted on the
object increases with the frequency of light used, then while the
objects rotation rate is increasing, I think the light passing through
will have a decreased frequency (less energy as energy is going into the
"flywheel".

Maybe they can make a new type of energy storage flywheel with this
technology, using Phil's numbers, 70pJ per object, in a 2D array on an
IC perhaps, with edge on circular polarized laser light. Need a way to
extract the rotational energy though. 4um diameter rotating objects,
say 10um X 10um for the object plus generator, that gives 10,000 per
mm^2 or 700nJ per mm^2. Increase that to a 10cm X 10cm die, and that
is 10uJ, and stack the ~0.1mm thick die into a stack of 1000 and that
is only 10mJ. So a 10cm x 10cm x 10cm cube would have only 10mJ of
storage in that case, and contain about 142 million little spinning
objects!

It could be useful for EM beam modification if you have a 3D grid of
little transparent spinning objects that can be spun up and down
electrically to modify a light beams characteristics, but if the overall
energy storage is only 10mJ, that can only make a big change on a weak
light beam probably.

cheers,
Jamie

 

[Uwe Hercksen]

Boy, I thought we were spinning stuff fast, up to 5000 RPS.
We are spinning little ceramic thimbles in an air bearing,
and it has little teeth machined in the side so an air jet
spins in.

Hello,

pcb drill machines are using up to 120,000 RPM or 2000 RPS.

Bye

 

[Uwe Hercksen]

Modified dentist's air drills? Dentists drills themselves don't spin nearly fast enough (500Hz), but it's a nice compact package designed to go into a confined space ...

pcb drills are faster, up to 2000 RPS. 0.2 mm diameter tools are too
small for a dentist, but not for small vias in a pcb.

Bye

 

[[email protected]]

pcb drills are faster, up to 2000 RPS. 0.2 mm diameter tools are too
small for a dentist, but not for small vias in a pcb.

According to Wiki, dentist drills operate up to 800,000RPM (13KRPS).

"Current iterations can operate at up to 800,000 rpm, however, most
common is a 400,000 rpm "high speed" handpiece for precision work
complemented with a "low speed" handpiece operating at a speed
that is dictated by a micromotor which creates the momentum
(max up to 40,000 rpm) for applications requiring higher torque
than a high-speed handpiece can deliver."