# Could a spacecraft be propelled by the deflection of a very high number of charged particles?

I am wondering if a spacecraft could be propelled through interplanetary space via the deflection and/or displacement of a very high number of charged particles contained within the Sun's solar wind.

The working principle of this propulsion idea is for an electric motor with two 'propellers' attached to it to be placed at the rear of a spacecraft. Say each propeller is 10 feet long. A strong permanent magnet, such as a 2 inch cube N52 neodymium magnet, would be attached to the tip of each propeller. The motor would rotate at 1 rps/60 rpm. During each revolution of motor's shaft, each magnet will travel a distance of 754 inches. Since each 2 inch magnet has a volume of 8 cubic inches, each magnet will pass through a volume of space equaling 3016 cubic inches during each revolution of the motor's shaft. 3016 cubic inches = 49423.39 cubic centimeters. The density of the charged particles in the Sun's solar wind is 5 charged particles per cm3 per second at 1 AU.

So, during each revolution of the motor's shaft, each magnet should either deflect away and/or displace 247,117 charged particles occupying that particular volume of space. Since every action has an equal and opposite reaction, the deflection of the charged particles should cause each magnet to move opposite the deflection of the charged particles thus pushing the magnets away from the Sun. The protons should flow around one side of the magnets and electrons should flow around the other side of the magnets, just like they do when they go around the Earth's magnetic field.

Also, I suspect that the strong magnetic field surrounding each 2 inch cube neodymium magnet will probably interact with charged particles up to a foot away from each magnet in all directions. If you consider that the charged particles may be affected by a magnetic field the size of a basketball for instance, and that the volume of a basketball is 455.9 cubic inches/7471 cubic centimeters, then each magnet should deflect away many more charged particles during each revolution of the motor's shaft and the thrust generated should be greater.

• I'd ask how you stop your spacecraft from spinning. But the volume multiplication doesn't work - if the magnet isn't there when the particle arrives, it doesn't interact.
– user20636
Jun 27 '18 at 1:54
• @JCRM, there are two ways that could keep the spacecraft from spinning. The first way is to use a counter-rotating propeller with the same number of magnets on it. The second way is to use counter-rotating flyweights.
– user26242
Jun 27 '18 at 11:38
• @Hobbes, I agree with you that 5 charged particles per cm3 per second is far too low to do anything and this is what lead me to come up with this idea. Going from 5 charged particles per second to 247,117 (and more) charged particles per second is much more ideal.
– user26242
Jun 27 '18 at 11:42

What you are describing is basically a permutation of the basic concept of a magnetic sail. You need a much bigger sail to get useful thrust, but it can just be a loop of superconductor carrying a current.

To see that the sail needs to be bigger, let's pick a number out of the air and suppose that your magnets could somehow "push away" 1 million protons per second. The mean velocity of the solar wind is 145 km/s, so lets assume we can "reflect" those particles and send them back towards the Sun at the same velocity. So we have velocity change of 300 km/s in 1 million proton masses per second. This amounts to a force onthe spacecraft of $$5\times 10^{-16} N$$ enough to accelerate the neodymium magnet (assuming the rest of the spacecraft has no mass) at about $$5\times 10^{-17}$$ gravities. It would take something over a billion years to go one meter. The problem is that protons are incredibly tiny. To get anywhere you need to accelerate a lot more of them (hence the huge magsails) or accelerate them close to the speed of light.

The use of permanent magnets rotation is a twist (pun intended) on the loop of current design. Three or more permanent magnets spaced around a circle but not rotating might do the same thing as a rotating pair, I'm not sure what the purpose of the rotation would be.

Not to be confused with electric sail or photon sail.

A magnetic sail or magsail is a proposed method of spacecraft propulsion which would use a static magnetic field to deflect charged particles radiated by the Sun as a plasma wind, and thus impart momentum to accelerate the spacecraft. A magnetic sail could also thrust directly against planetary and solar magnetospheres.

• I personally think that a lot of the proposed magsail ideas and the proposed solar sail ideas are too big and would be too expensive to build, deploy, and repair. I think my magsail design would be easy to build, deploy, and maintain/repair. Moreover, It would cost a lot less to build.
– user26242
Jun 27 '18 at 1:20
• I way I see it is that when a charged particle coming in from the Sun enters the magnetic field of the magnet, it will begin to curve away from the magnet. It will curve more the closer it gets to the magnet and a transfer of kinetic energy will be taking place during this time. The charged particle will then fly off away from the magnet at a new trajectory. Also, I am thinking that as charged particles are being curved away by the magnet as it moves forward, they will bump into other charged particles and the density of charged particles will increase, perhaps creating a bow shock.
– user26242
Jun 27 '18 at 11:50
• There is something that I would like to point out. In my description of my idea, I only used one magnet on each propeller, but the more ideal setup would be to use multiple permanent magnets on each propeller. For example, each propeller could be extended out to 20 feet and a 2 inch cube N52 neodymium permanent magnet could be placed along the propeller every two feet, so there would be five magnets on each propeller. The magnet positioned at the tip of this 20 ft propeller would travel a distance of 1508 inches per second, and the number of deflected charged particles per second goes way up.
– user26242
Jun 27 '18 at 12:11
• One more thing... I am thinking that the magnet and its magnetic field may also deflect and/or be impacted by other elements in the solar wind, such as atomic nuclei like helium/alpha particles, along with traces of 'heavy ions' and atomic nuclei of carbon, nitrogen, oxygen, neon and magnesium. The interaction with these elements would likely impact the overall thrust that would be created.
– user26242
Jun 27 '18 at 12:16
• Obviously there could be more magnets, but that means more mass. The heavier nuclei would add a little, but most of the solar wind is protons. However none of these effects are going to boost the thrust by the factor of a million million or so that you need. Jun 27 '18 at 12:55