
Extreme Light Intensities Using Optically Curved Relativistic Plasma Mirrors - bookofjoe
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.105001
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noobermin
Will read the paper later. It's interesting and the PIC sims which are state
of the art seem interesting, I really want to know how resilient the focusing
effect is to laser beam imperfections because that has been the bane of every
experiment pushing the high intensities over the last few years.

The idea iterates from a hot topic in intense laser plasma physics, an already
niche within a niche of fields. The idea is a "Plasma Mirror." In the world of
high intensity laser physics which means lasers essentially more intense than
1e14 W/cm^2 ( by comparison, sunlight at the earth's distance from the sun is
~0.1 W/cm^2) and such, they very quickly ionize the matter they interact with.
The lasers where "Plasma Mirrors" are relevant are even more intense than
this, say 1e16 and above. However, given you are playing with high magnitude
orders of intensity, you have long tails of intensity before the peak of the
pulse that are a few orders down (say, 1e14 W/cm^2) but are intense enough to
damage the target you want to interact with. The idea is to have a _thin
target of something_ before the main target in the optical path which acts as
a shutter. The idea is such, the probability in high field laser physics of
ionization essentially approaches one the higher the intensity of the incident
light. The thin target, called a plasma mirror, permits more low intensity
light below some threshold and starts to ionize when the intensity ramps up
well above 1e14, turning into a very good mirror. The effect is it only
reflects the higher intensity light, creating a cleaner, shorter pulse of high
intensity laser energy.

The second concept seems to be the geometrical shape of plasma mirror. I think
this is the new idea, because plasma mirrors have been here for a while. The
idea here seems to either statically or dynamically shape the plasma mirror so
it also focuses the light. I believe the record for high intensity is 2e22
W/cm^2. There are plans to create a near 1e24 W/cm^2 facility in Europe. The
sims here suggest an intensity of 1e25 W/cm^2, which is interesting for a
number or reasons, because it is near the point where this field starts to
touch strong field quantum effects, still a few orders down but approaching
the strong field region of QED.

To be critical, as usual, these are simulations, which is fine, but it will be
important to see how what physics they included in their simulations. Recent
literature has shown the traditional methods we use to model this physics
starts to break down as we increase the intensity of the laser above 1e24 or
so.

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petschge
4000^3 cells is extremely large for a PiC simulation and the dispersion free
Maxwell solvers are indeed state of the art (without them this simulation
would be impossible and scaling those solvers is quite hard), but the 2
particles per cell is worryingly low, even for a 3d simulation with high order
particles. Right now I can not read the supplemental material so I am not sure
to which degree this was validate with more particles in2d, but if nature does
not behave like this simulation, that is going to be the reason.

Source: I write PiC codes for a living.

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jasmcole
Pre print from arXiv:

[https://arxiv.org/abs/1812.05357](https://arxiv.org/abs/1812.05357)

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istjohn
What could someone use 10^25 W cm^-2 light intensity for? It that enough
energy to trigger fission and/or fusion in an appropriate target?

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jasmcole
One application (which I used to work on) is generating electric field
strengths beyond the 'Schwinger limit'. This is a field strength below which
various QED processes are exponentially damped, such as electron-positron pair
production. Generating such field strengths in the laboratory (as opposed to,
say, the surface of pulsars) will allow studies of strong-field QED.

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cromwellian
Useful for a high velocity laser-sail or say, an ice rocket?

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michaelsbradley
What’s the reference re: “ice rocket”? Google search turned up _Losers in
Space_.

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TrueDuality
Best bet I got is a reference to the book "Seveneves" which uses a nuclear
reactor buried in primarily ice asteroid. They consume the ice and use steam
essentially as a propellant.

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softbuilder
I see a hyperbole-filled abstract and a paywall.

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Beldin
Popular science write-up at Ars:
[https://arstechnica.com/science/2019/09/trampoline-mirror-
ma...](https://arstechnica.com/science/2019/09/trampoline-mirror-may-push-
laser-pulse-through-fabric-of-the-universe/)

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starpilot
mother of god

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moron4hire
All I know is that high intensity light could revolutionize large-scale 3D
printing.

~~~
noobermin
This is beyond that level of intensity of light relevant for that sort of
stuff.

