what concerns me is that it's wild laser beam in potentially public space.
anyone that would accidentally cross that potentially invisible line could get killed or severely hurt.
imagine something reflective entering this beam, it could blind people in a very large radius.
for me it means that thus would still need some pipe/fiber that would protect world from this laser.
seberino 44 minutes ago [-]
The eventual goal is to use it at extremely high altitude with drones so that that isn't much of a risk.
xattt 3 minutes ago [-]
[delayed]
DaftDank 15 minutes ago [-]
That will be quite a sight -- seeing the videos of people on the ground, filming future drone laser battles
inasio 8 hours ago [-]
“It’s a lot easier to send a power beam directly up or down relative to the ground because there is so much less atmosphere to fight through,” Jaffe explains. “For PRAD, we wanted to test under the maximum impact of atmospheric effects.”
Super impressive! My only complain is that this was done at the White Sounds desert in New Mexico, at over 1200 meters of elevation. For maximum impact they should have done it in Florida on a hot humid day
contrarian1234 3 hours ago [-]
＂maximum impact of atmospheric effects＂ would be simply a foggy day...
tnel77 49 minutes ago [-]
Both your example and theirs would be better tests than a desert.
PaulHoule 12 minutes ago [-]
The desert is bad enough. On a hot day you get convection which will vary the refractive index of light and spread out the beam. I wonder if they have active optics on the transmitter to fight this.
AndrewKemendo 8 hours ago [-]
There’s no range in Florida large enough for this test otherwise I’m sure they would have.
Even Eglin wouldn’t be large enough.
madaxe_again 7 hours ago [-]
Humidity would most likely attenuate the beam from 20% end to end to less than 1% - water vapour absorbs energy like nobody’s business.
This is a tech for arid environments - which seem to be where the US does most of its deployments these days.
3 hours ago [-]
jauntywundrkind 12 hours ago [-]
The application to drones seems most clear: beam drones some extra power as needed. Or continually!
I wonder how big that receiving apparatus is. Whether the receiver is gimballed, or whether the drone itself has to fly a heading to aim at the sender: TBD.
larodi 7 hours ago [-]
And have a great opportunity to drill some holes in birds heads.
Sorry I really fail to recognise how beaming 1kw of excited particles is a safe thing to do just like this…
7 hours ago [-]
worthless-trash 7 hours ago [-]
[flagged]
ChocolateGod 7 hours ago [-]
It must not be safe to be out in the sun then.
nkrisc 60 minutes ago [-]
It’s not, for an extended period of time. Now imagine it was collimated rather than diffuse.
kurble 10 minutes ago [-]
That's the thing, sunlight is collimated. It only gets diffuse once it reflects of a diffuse surface.
ben_w 2 hours ago [-]
Density (and wavelength), rather than total power, is important.
Sun's 1kW/m^2, and even then you shouldn't look directly at it, and being out in it all day without protection leads to sunburn.
_Algernon_ 6 hours ago [-]
Last time I forgot sunscreen at a UV index of 10 my skin started peeling of after half an hour so...
contrarian1234 3 hours ago [-]
Why not just beam power down the optical fiber? Optical fiber is exceptionally clear and works in fog and rain
malfist 3 hours ago [-]
Fiber transmits light, not rf. To get power out of fiber optics you have to have a photovoltaic cell on the other side and there's a limit for how much those can produce with such a collaminated light source.
Using fiber optics for power is like trying to make a solar panel generate electricity from a laser beam.
demod6 19 minutes ago [-]
"trying to make a solar panel generate electricity from a laser beam" is literally what the article is about.
TeMPOraL 3 hours ago [-]
> Using fiber optics for power is like trying to make a solar panel generate electricity from a laser beam.
Isn't that exactly what power beaming is, except typically with frequency range in microwaves instead of visible light?
contrarian1234 3 hours ago [-]
just have a tiny steam turbine equivalent...? (some thermoelectric generator) You don't really need to be efficient. You have fans to blow air and dissipate heat on the other end after all
0_____0 2 hours ago [-]
You should do the first round of engineering calculations on this.
ben_w 2 hours ago [-]
I have no idea why this might be limited by the light source being collimated?
I mean, you can get electricity from PV illuminated by a laser, and everything I've heard so far says it's easier than with sunlight because you can match the frequency of the laser to the band gap of the PV.
Maxsnijders 2 hours ago [-]
If you were to go that way, why not a wire?
Traubenfuchs 6 hours ago [-]
How about drones with a solar panel case? Would require a sunny day to work at all though.
Tiny nuclear reactor?
ben_w 2 hours ago [-]
On the scale that useful nuclear reactors operate, a "tiny nuclear reactor" is the size of a shipping container.
Even a tiny RTG is in the same range as a dumbbell.
Traubenfuchs 2 hours ago [-]
While not reactors, how about nuclear batteries without heavy shielding?
ben_w 1 hours ago [-]
Nuclear batteries are a superset of RTGs.
There are other kinds of nuclear battery, but the ones I've heard of outside labs, are extremely low power betavoltaics.
Traubenfuchs 6 hours ago [-]
[flagged]
petermcneeley 11 hours ago [-]
"reflects onto dozens of photovoltaic cells arranged around the inside of the device which convert the energy back to usable power."
This is no different that what we were considering two decades ago for the space elevator competition. One of the problems with this approach is that as the photovoltaic cells heat up their overall efficiency decreases.
bagels 9 hours ago [-]
They'll only get so hot, and you can just spread the energy across more cells, right?
westurner 1 hours ago [-]
Is it possible to steer the weather by heating the atmosphere with power beaming microwaves?
Is it possible to cancel the vortical formation of a tornado or a hurricane with microwave power beam(s)?
Does heating the atmosphere with microwaves change the weather, or the jet stream, or the cloud cover?
What sort of a fluidic weather simulator could answer this question?
Is there a fluid simulation device that allows for precise wireless heating of certain points in the fluid?
If so, there could be international space law to study and control for the known and presumed risks of space-based microwave power beaming.
I think it's possible to nuke a tornado, but if someone does it to try to save a city, I expect even more destruction.
I don't expect the beam to be energetic enough to change anything. The closest method I can think of is https://en.wikipedia.org/wiki/Cloud_seeding but it doesn't distribute energy, just tiny crystals to condense oversaturated vapor.
ChrisMarshallNY 4 hours ago [-]
> New Mexico
Great stuff.
Do Seattle, next.
janalsncm 12 hours ago [-]
Could this also be a viable alternative to HVDC lines for civilian applications?
theamk 12 hours ago [-]
No. 800 watts (vs megawatts for HVDC). 5 miles vs thousands of miles. 20% efficiency optical to electrical - so electrical vs electrical is much worse - vs 90%+.
This is so much worse in every aspect it's not really compareable.
naruhodo 8 hours ago [-]
It's great if you hate birds, though.
_fizz_buzz_ 23 minutes ago [-]
This can only be used where efficiency doesn't matter, like military applications for powering a drone. The overall efficiency i.e. grid -> laser -> pv -> grid would be atrocious.
other_herbert 12 hours ago [-]
The key thing they aren't saying is how much power it took to "send" 800 watts 5.3 miles...
bracketfocus 12 hours ago [-]
They mentioned that it was 20% efficient at a closer distance.
So likely much lower than that.
PaulHoule 7 minutes ago [-]
20% efficiency in terms of light -> electricity. A 50% laser efficiency (electricity -> light) is really good, possible for some diode lasers, if you pump a fiber laser with diodes to get a high quality beam for cutting materials or weapons purposes maybe you get 25%.
That demo would require about 45 kW of laser power with good beam quality which would be totally possible with a fiber laser
Wow that's a long way from the proposals for sending GW of microwave power from satellites.
aurizon 2 hours ago [-]
Those sat to ground power sources use gallium arsenide switched FETs = synchronous rectification, avoiding the voltage drop of diodes has been tested on a small scale, the 10GW orbital 35% efficient solar arrays, maybe next week... Solar boilers, end to end, are more efficient than solar cells, but mechanical complexity(leaks, corrosion, worker avarice) made one US plan in the South West non viable. As we sit silicon-perovskite tandem solar cells will top out around 42-45% - unless Schockley is end runned? Ternary -??.
A good lecture = https://www.youtube.com/watch?v=Ft0VJX0_Td0&t=2s&ab_channel=...
PaulHoule 3 minutes ago [-]
Solar thermal as well as solar-chemical systems have the problem of start-up.
PVs do not have any problem starting up, they produce less than full power with less than full illumination but they produce something and once the illumination is full they produce full power immediately.
Many solar thermal power plants are fired with natural gas in the morning to get them spun up to the point where they can take advantage of the solar energy. Without that they'd probably lose a few hours of production.
conradev 8 hours ago [-]
But pretty close to powering drones from ground stations
pfdietz 10 hours ago [-]
Laser power beaming from space could be useful at lower power levels than that, for example for powering aircraft.
HenryBemis 5 hours ago [-]
I was thinking of"how much is enough" so they can power 'instruments'. I am also thinking of 'how can we use this tech to revive space-instruments (the next generation of 'Voyagers' may be equipped with such receivers?)
I also wonder how difficult/impossible would it be, and the 'throughput'. Assuming that you want to recharge a recon drone (or the 'next generation of Voyagers flying in space) that flies over XYZ area/country/etc. Would it take 1sec or 10seconds 'of beam', and the accuracy/waste/total amount one would have to 'dispense' in order to give that drone the X seconds of 'juice' to keep it running for 1000x X seconds of flight duration. And what about clouds/mist/rain/snow/birds/etc.
'Infinite energy' for a drone (I mean no dependency to come down to refuel) is a game changer.
Would that work with 'instruments buried underground? And at what depth? ('War of the worlds' scenario). Could someone bury a device, with only the receiver protruding from the ground, with a battery to keep it alive, and waiting to be activated by a satellite passing by giving it the "10 seconds beam" to fully charge it and.. (I am thinking of the recent drone-related incidents/attacks within Russia and Iran)(if you park a drone for 10 months, its battery will deplete, right?)(I don't have a drone, but batteries are batteries).
A second thought on the matter, can one 'program' the light to be also transferring data? Park the drones in <insert foreign territory>. No programming. In the middle of nowhere (no 4G-5G). You fly a satellite over it, beam down the 'juice' (together with the instructions - no interception of the transfer is possible). Someone finds it 'before', they only get the hardware but no info/intel.
"The possibilities are endless" (and so are the nightmares)
cryber 6 hours ago [-]
The popcorn is a very nice touch
b00ty4breakfast 11 hours ago [-]
This seems very silly. It's either a death ray project in a fake mustache or somebody had earmarked a bunch of money that they had to spend before it expired.
kulahan 11 hours ago [-]
This is kinda surprising to read. I’ve never known anyone who isn’t incredibly excited at least at the prospect of wireless energy transfers. If you can do 800 watts over 8 km, surely we can do 150 watts across 3 feet in the household, and MANY of our most important discoveries come from DARPA essentially being a black budget skunkworks team.
But much of the stuff DARPA does seems weird. It’s not about ideas with solid foundation and thorough engineering, it’s about crapshoots that might work and would pay off in some way - often any financially feasible way.
They once put “cats” on guns in hopes it would surprise opponents even just for a quarter second, giving your spec ops dudes the advantage. They tried to create angled guns that could shoot around corners like 20 years ago. All kinds of crazy stuff! It would be a lot of fun to work there, I think.
robertlagrant 4 hours ago [-]
> They tried to create angled guns that could shoot around corners like 20 years ago
The IDF got a gun that does this[0] into service in 2003.
The actual work is usually done by private companies under contract
10 hours ago [-]
christkv 8 hours ago [-]
The germans tried the curved gun with an attachment called Krummlauf during ww2. It would break after just a couple of magazines being fired. https://en.wikipedia.org/wiki/Krummlauf
Not sure how you would build one of those without the stress of the bullet during firing would not damage the barrel.
alanbernstein 6 hours ago [-]
I'm amazed that worked for even one shot. Presumably gp was referring to cornershot or something similar, which seems like a much more reasonable approach.
imagine something reflective entering this beam, it could blind people in a very large radius.
for me it means that thus would still need some pipe/fiber that would protect world from this laser.
Super impressive! My only complain is that this was done at the White Sounds desert in New Mexico, at over 1200 meters of elevation. For maximum impact they should have done it in Florida on a hot humid day
Even Eglin wouldn’t be large enough.
This is a tech for arid environments - which seem to be where the US does most of its deployments these days.
I wonder how big that receiving apparatus is. Whether the receiver is gimballed, or whether the drone itself has to fly a heading to aim at the sender: TBD.
Sorry I really fail to recognise how beaming 1kw of excited particles is a safe thing to do just like this…
Sun's 1kW/m^2, and even then you shouldn't look directly at it, and being out in it all day without protection leads to sunburn.
Using fiber optics for power is like trying to make a solar panel generate electricity from a laser beam.
Isn't that exactly what power beaming is, except typically with frequency range in microwaves instead of visible light?
I mean, you can get electricity from PV illuminated by a laser, and everything I've heard so far says it's easier than with sunlight because you can match the frequency of the laser to the band gap of the PV.
Tiny nuclear reactor?
Even a tiny RTG is in the same range as a dumbbell.
There are other kinds of nuclear battery, but the ones I've heard of outside labs, are extremely low power betavoltaics.
This is no different that what we were considering two decades ago for the space elevator competition. One of the problems with this approach is that as the photovoltaic cells heat up their overall efficiency decreases.
Is it possible to cancel the vortical formation of a tornado or a hurricane with microwave power beam(s)?
Does heating the atmosphere with microwaves change the weather, or the jet stream, or the cloud cover?
What sort of a fluidic weather simulator could answer this question?
Is there a fluid simulation device that allows for precise wireless heating of certain points in the fluid?
If so, there could be international space law to study and control for the known and presumed risks of space-based microwave power beaming.
I think it's possible to nuke a tornado, but if someone does it to try to save a city, I expect even more destruction.
I don't expect the beam to be energetic enough to change anything. The closest method I can think of is https://en.wikipedia.org/wiki/Cloud_seeding but it doesn't distribute energy, just tiny crystals to condense oversaturated vapor.
Great stuff.
Do Seattle, next.
This is so much worse in every aspect it's not really compareable.
So likely much lower than that.
That demo would require about 45 kW of laser power with good beam quality which would be totally possible with a fiber laser
https://www.rp-photonics.com/wall_plug_efficiency.html
PVs do not have any problem starting up, they produce less than full power with less than full illumination but they produce something and once the illumination is full they produce full power immediately.
Many solar thermal power plants are fired with natural gas in the morning to get them spun up to the point where they can take advantage of the solar energy. Without that they'd probably lose a few hours of production.
I also wonder how difficult/impossible would it be, and the 'throughput'. Assuming that you want to recharge a recon drone (or the 'next generation of Voyagers flying in space) that flies over XYZ area/country/etc. Would it take 1sec or 10seconds 'of beam', and the accuracy/waste/total amount one would have to 'dispense' in order to give that drone the X seconds of 'juice' to keep it running for 1000x X seconds of flight duration. And what about clouds/mist/rain/snow/birds/etc.
'Infinite energy' for a drone (I mean no dependency to come down to refuel) is a game changer.
Would that work with 'instruments buried underground? And at what depth? ('War of the worlds' scenario). Could someone bury a device, with only the receiver protruding from the ground, with a battery to keep it alive, and waiting to be activated by a satellite passing by giving it the "10 seconds beam" to fully charge it and.. (I am thinking of the recent drone-related incidents/attacks within Russia and Iran)(if you park a drone for 10 months, its battery will deplete, right?)(I don't have a drone, but batteries are batteries).
A second thought on the matter, can one 'program' the light to be also transferring data? Park the drones in <insert foreign territory>. No programming. In the middle of nowhere (no 4G-5G). You fly a satellite over it, beam down the 'juice' (together with the instructions - no interception of the transfer is possible). Someone finds it 'before', they only get the hardware but no info/intel.
"The possibilities are endless" (and so are the nightmares)
But much of the stuff DARPA does seems weird. It’s not about ideas with solid foundation and thorough engineering, it’s about crapshoots that might work and would pay off in some way - often any financially feasible way.
They once put “cats” on guns in hopes it would surprise opponents even just for a quarter second, giving your spec ops dudes the advantage. They tried to create angled guns that could shoot around corners like 20 years ago. All kinds of crazy stuff! It would be a lot of fun to work there, I think.
The IDF got a gun that does this[0] into service in 2003.
[0] https://en.wikipedia.org/wiki/CornerShot
[0] https://www.imdb.com/title/tt0493464/
Not sure how you would build one of those without the stress of the bullet during firing would not damage the barrel.