[CORRECTIONS ABOUND! It isn't as bad as my first napkin suggests.]
Well done scientists[1]! Cue the engineers…
And it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn't this intense on its own…
Sunlight is about 1000watt/m^2. They are using 100 billion watts/m^2. That is, you would need to concentrate sunlight to 100 million times to reach this level.[2]
Put another way, if your fiber is about 1mm in diameter, you will need a perfect[3] mirror array 10 meters in diameter to drive it[4]. [CORRECTED from 400 meters, thanks to loup-vaillant]
Wild speculation follows:
• This has got to be used in pulsed mode. 100 kilowatts down a 1mm optical fiber is going to vaporize it if done for more than a tiny fraction of a second. Are there the optical equivalent of super conductors that are suitable for this?
• I went with a 1mm fiber because it "only" required a 10m mirror to drive it, but at what voltage are we going to get 100 kilowatts of power out of a non-conductor with a 1mm^2 cross section? Sounds like 50 zillion is the answer.
• Lets guess 10% efficiency, and the rest comes out as light at the end of the fiber (so our fiber doesn't turn to plasma). Where are you going to point that? I suppose into a light tight chamber contained in the molten salt loop of a steam power plant would be a good start.
• Maybe this all works better at the nano scale. Heat dissipation is easier since essentially all of the optical media can be in contact with heat sink. The mirrors get smaller to achieve the required light density. There is a shape, sort of stretched parabolic looking, that is a non-imaging optical funnel which might get your light all gathered to the same point, albeit going in a variety of direction. The total power would be lower, lowering the voltage required, letting you use sane power converters.
[1] And yet again, you have degraded the value of my undergraduate education by falsifying my hard learned facts.
[2] I may well have lost a zero or more each way. It's early. Don't use these calculations to place orders for mirrors.
[3] From 10+ meters away it is going to have to focus to a 1mm target. [CORRECTED from 200+, it doesn't sound so bad now]
[4] On proofreading I see I have a [4] footnote, in the text but no corresponding note. It was probably vaporized by a poorly aimed fiber.
…but… if we don't rely on spatial compression to achieve the density, but instead use temporal compression…
1) Consider a mirror which rotates through n angular positions.
2) At position zero it reflects off "secondary mirror #0" and onto our target at X microseconds.
3) At position one it reflects off "secondary mirror #1" and onto our target at X-k microseconds.
4) At position n it reflects off "secondary mirror #n" and onto our target at X-k * n microseconds.
5) If we turn the rotating mirror from position 0 to 1 after k microseconds, we have darkness on the target for X microseconds, then light from both secondary mirrors 0 and 1 for k microseconds.
6) If we rotate through all n positions at k microseconds/position we get n times the light at a 1/n duty cycle.
7) As n goes to infinity: PROFIT!
Mathematicians might solve for the shape of the now continuous secondary mirror. I would just write a javascript program to approximate it for segments of length epsilon. Ultimately the CNC equipment that makes the mirror will have an epsilon anyway.
You may wish to use a mirrored polygon to sweep the usable angle of your secondary mirror repeatedly.
Yes! It wasn't until lunch when it dawned on me that viewed backwards it made a time dilation device. I fear the continuous version could not be reconciled with imaging optics, but for non-imaging applications it can slow down an event for more leisurely capture.
I didn't go to University, and wasn't much for science in high-school, but (using your figures) sunlight is 1000watts/m^2/second (or millisecond or minute), isn't it?
If so, aren't your concerns about the size of the mirror, etc. imposing a limitation, kinda like saying we can build a jet that will fly from NYC to San Fran in 30 seconds, but we can't keep the people in one piece during the trip. Therefore, we slow it down to a more humanly acceptable speed. With the volume of sunlight hitting the planet, would we not be able to take only a portion of that sunlight and concentrate it over time to get the same effect??
Of course, like an airplane, you need a minimum speed to create lift, and this magnetic effect may have such a limiting speed/force(?).
Of course, I have no idea what I'm talking about, but you seem quite knowledgable.
watts is a measure of power. The often confused "kilowatt hour" is a measure of energy and would indeed need the time "/second" (or other time unit) added. But I am working in power here.
would we not be able to take only a portion of that sunlight and concentrate it over time to get the same effect
Yes! We went the same way here. I replied to the parent comment with a description of a temporal light concentrator.
I've never heard of such a device, maybe people that know the name of them can order them from a catalog, but it is an intriguing solution because it solves the "massive collector" problem as well as the "holy sh*t! what am I going to do with all this waste heat!" problem.
It's also possible that people more comfortable with light as a wave spit coffee out of their nose and had a good laugh when they read it.
I didn't go to University, and wasn't much for science in high-school, but (using your figures) sunlight is 1000watts/m^2/second (or millisecond or minute), isn't it?
No, sunlight is 1000 watts / m^2, or 1000 joules per square metre per second. The Watt is a unit of power (ie energy over time).
As a footnote, there is a pitfall here in the English language.
The word "over" might mean divided by, or it might mean "integrated across", which are, in the case of constant power completely opposite meanings.
power is energy ÷ time (assuming the power is constant, and thinking of horizontal lines for fractions you might say "power is energy over time")
energy is power × time (assuming the power is constant, but if you are thinking "integration" you might say "energy is power over time")
[3]: Err: 100m² are enough get the 100M concentration on the square millimetre, right? A perfect lens of that surface would only need to be about 11 meters in diameter. Error on your part, or did I miss something?
Here, we expect to have a very low heat load. Instead of the light being absorbed, energy is stored in the magnetic moment. Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power source.
Well done scientists[1]! Cue the engineers…
And it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn't this intense on its own…
Sunlight is about 1000watt/m^2. They are using 100 billion watts/m^2. That is, you would need to concentrate sunlight to 100 million times to reach this level.[2]
Put another way, if your fiber is about 1mm in diameter, you will need a perfect[3] mirror array 10 meters in diameter to drive it[4]. [CORRECTED from 400 meters, thanks to loup-vaillant]
Wild speculation follows:
• This has got to be used in pulsed mode. 100 kilowatts down a 1mm optical fiber is going to vaporize it if done for more than a tiny fraction of a second. Are there the optical equivalent of super conductors that are suitable for this?
• I went with a 1mm fiber because it "only" required a 10m mirror to drive it, but at what voltage are we going to get 100 kilowatts of power out of a non-conductor with a 1mm^2 cross section? Sounds like 50 zillion is the answer.
• Lets guess 10% efficiency, and the rest comes out as light at the end of the fiber (so our fiber doesn't turn to plasma). Where are you going to point that? I suppose into a light tight chamber contained in the molten salt loop of a steam power plant would be a good start.
• Maybe this all works better at the nano scale. Heat dissipation is easier since essentially all of the optical media can be in contact with heat sink. The mirrors get smaller to achieve the required light density. There is a shape, sort of stretched parabolic looking, that is a non-imaging optical funnel which might get your light all gathered to the same point, albeit going in a variety of direction. The total power would be lower, lowering the voltage required, letting you use sane power converters.
[1] And yet again, you have degraded the value of my undergraduate education by falsifying my hard learned facts.
[2] I may well have lost a zero or more each way. It's early. Don't use these calculations to place orders for mirrors.
[3] From 10+ meters away it is going to have to focus to a 1mm target. [CORRECTED from 200+, it doesn't sound so bad now]
[4] On proofreading I see I have a [4] footnote, in the text but no corresponding note. It was probably vaporized by a poorly aimed fiber.