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But you would also have an accumulation of negative charge somewhere. What do you do with that?

Lint rollers.
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Very heavy particles if you can project them in a stream

Which would make everything behind the rocket radioactive.

When I was an undergrad we did a modern physics experiment. We put silver samples (old dimes if I remember correctly) next to a neutron source (Americium-241). After the silver had cooked for several minutes, we ran them over to our Geiger counters to measure the radioactive decay. Literally ran: the half-life of the produced isotopes was measured in seconds. I took the following lessons from this experiment:

1. Radioactive decay does follow an inverse exponential curve, just like they taught us in class.
2. Neutron sources make other things radioactive, and thus have to be heavily shielded.

Even if, hypothetically, you could make your proposed neutron stream, it’s a really bad idea.

Regards,

- HCF
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pauleckler,

You wrote, Neutron density is put at 10^17 kg/m^3 = 10^8 g/cm^3.

Very heavy particles if you can project them in a stream/


Yeah. But that last part kind of ignores what we know of physics. You can't use the electromagnetic force to confine neutrons into a beam and any matter you use as a reflector or containment vessel is going to tend to absorb the neutrons ... if they don't just pass right through the material.

Also the efficiency of a rocket exhaust is measured in specific impulse (Isp: https://en.wikipedia.org/wiki/Specific_impulse), which is a function of the mass and exhaust velocity. Higher mass exhaust products must be expelled at correspondingly higher exhaust velocities to achieve the same efficiency.

Thermal nuclear rocket designs tend to heat hydrogen to a plasma and expel that. The high heat of the exhaust helps produce a high Isp; but the fact that the propellant is low mass allows you to achieve high efficiency without requiring temperatures (or pressures) that might cause issues with known materials. If you increase the mass of the exhaust propellant you also need to increase the temperature and pressure, which creates new problems...

Trying to confine a neutron stream adds yet another problem to the mix - one we don't have the science for, AFAIK.

- Joel
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Yes, protons and neutrons are perhaps the heaviest items on earth. All matter is made up of atoms which are mostly clouds of almost weightless electrons. The nucleus of protons and neutrons has almost all the weight.

You could try for protons instead. Then you could attract and direct them with their positive charge. But you would also have an accumulation of negative charge somewhere. What do you do with that? That's why I thought a neutron gun would be most practical. But so far there seem to be some technical difficulties to resolve.

Looks like the Ruskies are using mere thermal expansion. Nothing fancy.
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But you would also have an accumulation of negative charge somewhere. What do you do with that?

Lint rollers.
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