[HN Gopher] Transferring energy from nitrogen to argon enables 2...
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Transferring energy from nitrogen to argon enables 2-way cascaded
lasing in air
Author : wglb
Score : 62 points
Date : 2024-08-25 02:46 UTC (20 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| dynjo wrote:
| Are we one step closer to lightsabers?
| alsaaro wrote:
| Or sci fi holograms?
| at_a_remove wrote:
| Exploring this, I think lightsabers would be Really Hard. Not
| transporter-level hard, but still tough. I see two paths:
|
| 1) Using actual photons in something laser like. The problem
| here is that your lightsaber would go on forever, photons won't
| just peter out after a meter or so. So, you would need, well,
| something to "cap" the lightsaber, both as a cap in terms of
| ending something, and a cap as in "capture" or possibly even
| "reflect." So you would need a teensy something floating at the
| end of your lightsaber, perfectly synchronized with the
| positions and velocities of the hilt. Also, small enough not to
| make a viable target for hitting with some other light saber in
| your duel. It would either be suspended by antigravity or as
| some kind of tiny drone.
|
| 2) Your other alternative is that your lightsaber is really
| some kind of plasma bottle, a hideously distorted ellipsoidal
| electromagnetic confinement field. This has its own problems,
| like your blade not wildly changing shape near metal or if
| someone throws a refrigerator magnet at your odd Jedi or Sith.
| You _might_ be able to compensate with some kind of high-speed
| computations accounting for the magnets and such on the fly and
| "fixing" the distortions as they occurred. The plasma would be
| quite different from the plasma you might see in hopeful fusion
| projects. It would have to be quite hot and dense, eager to
| dump energy. This might also benefit from the "cap" in the
| first one.
|
| I could see blasters being a little more likely. Your plasma
| packet could be self-propagating and you would not have to
| worry about its stability over multiple seconds and such. Each
| plasma packet might also benefit from the aforementioned caps,
| one on each end, zipping toward the target and simply
| destabilizing when the target is reached, releasing all of the
| energy at once, rather than the buttery-smooth slices of
| lightsabers.
|
| 3) Circling back, perhaps some esoteric corner of yet-to-be-
| discovered physics might allow for temporary bosons (the boson
| nature of photons is what allows for lasers to really do their
| thing), so perhaps there is some unknown cousin of the photon
| which could be coaxed into lasting for roughly three and a
| third nanoseconds (or one meter, take your pick), And hopefully
| it can come in green, blue, purple, and red.
| ganzuul wrote:
| A diffraction grating made up by free electrons could do it.
| Alternatively total internal reflection by heating a volume
| with a phased array.
|
| At least that's how we used to do it a long, long time ago.
| actionfromafar wrote:
| were you far away?
| r2_pilot wrote:
| Considering how long free electron lasers have to be for
| the wigglers to work, I'd imagine so. But if you can get
| electrons to oscillate fast enough in a small enough
| distance, hit me up.
| meindnoch wrote:
| >Using actual photons in something laser like. The problem
| here is that your lightsaber would go on forever, photons
| won't just peter out after a meter or so. So, you would need,
| well, something to "cap" the lightsaber, both as a cap in
| terms of ending something, and a cap as in "capture" or
| possibly even "reflect."
|
| What about using a proton beam, and exploiting the Bragg peak
| to ionize a finite-length column of air?
| at_a_remove wrote:
| Well, protons beat out electrons for at least keeping the
| divergence down, any volume of lightsaber with a net charge
| is still going to be vulnerable to fridge magnet attack.
| Also, I have a strong feeling that it wouldn't _look_ very
| lightsaber-ish. More like a rapier, although I guess for
| aesthetic purposes you could have scores of little
| emissions tubes and switch between them on the order of
| milliseconds and hope that persistence of vision would
| create an illusion of thickness.
|
| I have a feeling that the sudden stop could be _nasty_ for
| even the person holding the hilt, just tons of energy
| spraying wildly around, a big enough radiation vacation
| that even the Hulk might blanch at soaking up the gammas.
| It would still technically qualify as handheld melee arm,
| but it would be so indiscriminate as to be an inelegant
| weapon of a more _un_ civilized age.
| GolfPopper wrote:
| Current lightsaber designs are all gas/plasma at the cost of
| blade stability. [1][2] They look pretty cool and can cut
| things, though.
|
| [1]https://www.youtube.com/watch?v=xC6J4T_hUKg
| [2]https://www.youtube.com/watch?v=RSSAhmmiZjM
| sandworm101 wrote:
| Or, use flame as the plasma. Confine the plasma with magnets
| and let the burn time set the length. It could look and act
| the part, but wouldnt involve actual lasers.
| api wrote:
| More efficient lasers are the big barrier to inertial
| confinement fusion, which IMHO is much cooler given the
| implications: cheap clean energy forever and awesome fusion
| torch rockets.
|
| https://en.m.wikipedia.org/wiki/Inertial_confinement_fusion
|
| https://en.m.wikipedia.org/w/index.php?title=Nuclear_pulse_p...
| jerf wrote:
| If you search over YouTube, you'll find many people who have
| built one aspect or another of a lightsaber. There are things
| that look like lightsabers, but can't collide with each other.
| There are things that look like lightsabers, but can't collapse
| into a hilt. There are things that dump energy like lightsabers
| but don't fit into a dapper little hilt.
|
| It may just be a matter of perspective, but if you spend enough
| time with the various options, you may well come away with a
| much better perspective on why you're never going to have
| anything just like them. You might think seeing the
| possibilities would make it more likely, but you'll also see
| just what it would take to be all these things at once.
| charliewallace wrote:
| at 261nm, this is far ultraviolet light
| yorwba wrote:
| Multiple other wavelengths are involved:
|
| > Superfluorescent lasing occurs on cascaded 1327.3 nm (1st
| lasing) and 840.8 nm (2nd lasing) transitions.
|
| > Subsequently, superfluorescent lasing occurs on cascaded
| 1409.4 nm (1st lasing) and 751.5 nm (2nd lasing) transitions.
|
| ... but these are infrared, so still no visible laser.
| pixl97 wrote:
| Anyone concerned about their eye health should be very
| worried about invisible lasers too. You won't notice you're
| cooking your eyeballs.
|
| Owned night vision and an IR laser at one point.
| CoastalCoder wrote:
| > Owned night vision and an IR laser at one point.
|
| Could you clarify how this relates to your first statement?
| mandmandam wrote:
| I would imagine that IR lasers come with large and scary
| warnings about the dangers of cooking anyone's eyes; and
| that night vision lets you see the unexpected paths that
| an IR laser can take, bouncing off reflective surfaces
| and such.
| adrian_b wrote:
| The free variant of the research paper:
|
| https://arxiv.org/abs/2405.04089
| pfdietz wrote:
| The old Amateur Scientist column in Scientific American had (in
| June 1974, half a century ago) an installment on how to build a
| pulsed nitrogen laser. It wasn't that hard. The emission is in
| the ultraviolet.
|
| https://www.jstor.org/stable/24950104
|
| https://diverdi.colostate.edu/C431/experiments/time%20domain...
|
| https://www.jonsinger.org/jossresearch/lasers/nitrogen/circu...
|
| https://www.youtube.com/watch?v=pCnXftuJ9Zo
| tonetegeatinst wrote:
| Possible new power source for UV lithography for semiconductor
| manufacturing. No more hitting tin with a laser many?
| emchammer wrote:
| Look at how cool the last guy's home lab is! I sincerely hope
| that we are encouraging high schoolers to get into this kind of
| stuff.
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