# Can you generate energy from particles in space?

I am making design of a fictional doomsday weapon which is like a miniature version of Death star's beam. I.e it can rip apart chunks of planet and impart significant change in its mass.

However I also want it to be as much believable in for a future setting as possible instead of something running off magic

So in a distant future from now is it possible to gather energy from charged particles and other quantum phenomenon in outer space except solar panels.

Like the charged particles ejected from solar wind , can they be used for generating a potential difference of the order of several million or billion volts and several million amperes and use it fire the weapon for a short burst.

Just how much energy can you get from particles in radius of a few hundred kilometres in space in our solar system?

## Solar Wind

First of, let's look at what solar wind is:

The solar wind is a stream of charged particles released from the upper atmosphere of the Sun. This plasma consists of mostly electrons, protons and alpha particles with energies usually between 1.5 and 10 keV; embedded in the solar-wind plasma is the interplanetary magnetic field.

What is 10 keV? Not much... $1.60218 \times 10^{-15}$Joule in kinetic energy, and these particles are pretty small. Also there is a continious stream of these, and they do in fact create a pressure, that would be enough to move heavy objects outwards from the solar system, if these would have a large enough surface: They create a pressure of $\text{P}=1.6726 \times 10^{-15} \times n \times (\vec{v} \times 3.6)^2$ wherein n is the flow density in $\frac{1}{cm^3}$ and $\vec v$ is the speed of the particles in $\frac m s$. At eatrth orbit that is between 1 and 6 Nanonewton per square Meter $(10^{-9} \frac {N} {m^2})$.

To achieve the Force of 1(to 6) Newtons to be converted to energy, one would need to use a sail in the area of $10^9 m^2$, so about a square with a side of 31.6227 kilometers. Or a circle with about 17.8412 kilometers in radius (or a diameter of 22.17 miles).

Now, how to turn 1 Newton of force outwards of the solar system into something useable? One could use it to navigate the doomsday device outwards. One could use it to very very slowly bring th edoomsday device up to some speed and then use it as an impactor on some other soilar system, several million years later. But that is not feasable. Can it be used to power a machine needeing thousends of millions of volts? No. And to power a massive 'solar wind turbine' it is by far not dense enough.

So Solar wind is out.

## Photon Power!

What is the next in line? Just using uncharged particles. Best we use Photons, which do in fact act as particles, especially if they interfere with silicon layers... Yes, our doomsday device could be powered by a massive solar farm charging batteries for the shot.

Now, numbers check. Solar light at the earth orbit delivers about $1337 \frac W m^2$, which is substantial. Even with 20% efficiency for solar cells, that would give something in the size of $237.4 \frac W m^2$, or as Volts are Watt per Ampere: $237.4 \frac V {A \times m^2}$. If you know how much Energy per second your doomsday device will need to be fired (which actuallyjust plain old Watts: $W=\frac J s$), you can calculate how big its associated solar farm will need to be for continious running. The answer is probably huge, and you will have to account for storeage efficiency, minimum operation load (which eats on what you can actally store) and tons of other factors, but the area might be still small enough to not break under the tension the aforementioned solar wind applies. And you have to come up with some sort of heat dissipation system, as solar panels run hot, and space is notoriously bad at dissipating heat, even if it is just 2-3 Kelvin 'warm'.

But there is an even simpler and cheaper solution: Mirrors & lenses. If your doomsday device is a set of mirror sattelites that can focus the light, they can bundle up to become a pretty deadly source of energy. While they might not be enough to melt a planetary crust or blow the planet to pieces, it can be enough to just tilt the ecosystems off balance and doom the planet to become a desert by increasing its efficient temerature (by acting as a secondary "sun"). Just get the system cooled and it will fire as long as the sun exists... and the sattelites are properly aimed.

This doesn't look practical for any normal kind of star. While the solar wind contain quite a few charged particles, they are a mixture of positive and negatively charged ones, and it averages to neutral charge. If it didn't, stars would accumulate huge electrical charges, and they don't.

The momentum of the solar wind can give you a small amount of energy - that's what solar sails would use - but the energy density is very low, and you'll never build up the kind of power you're after from it.

Now, there may be kinds of star where you could get more energy out of the solar wind, but they probably aren't ones that have life-bearing planets worth attacking with a superweapon. You need a power source to run it.