Comments on: This tokamak produces magnetic bubbles called plasmoids that move at around 20 kilometers per second

By: Sindarian

Sindarian — Wed, 17 Feb 2021 18:52:25 +0000

f=ma

The more (a) acceleration you have, the less (m) mass you need to get the same (f) force. The less mass you need to get to point B from point A the more mass you have for cargo or life support.

By: Gavin Longmuir

Gavin Longmuir — Mon, 15 Feb 2021 01:56:46 +0000

The article was probably written by a Harvard graduate, so we should be pleased that the spell corrector worked and not expect too much in the way of understanding of physics. The process presumably makes more sense than the article, which left me with some questions:

“Second, the new thruster produces movement by ejecting both plasma particles and magnetic bubbles known as plasmoids. The plasmoids add power to the propulsion and no other thruster concept incorporates them.”

What is the mass of a plasmoid? If a magnetic bubble has no mass, then it is not going to have momentum, and hence would not add to the reaction force.

“Third, … the magnetic fields in Ebrahimi’s concept allow the plasma inside the thruster to consist of either heavy or light atoms. … “While other thrusters require heavy gas, made of atoms like xenon, in this concept you can use any type of gas you want,” Ebrahimi said. Scientists might prefer light gas in some cases because the smaller atoms can get moving more quickly.”

A light particle moving quickly would have similar momentum to a heavy particle moving much more slowly. Where is the advantage in terms of the reaction thrust?

By: Wang Wei Lin

Wang Wei Lin — Mon, 15 Feb 2021 01:12:58 +0000

Given there is no free lunch in physics, how does this differ than any other propulsion system that converts mass into thrust? Once out of the gravity well of earth the laws of physics remain the same so that the total energy needed to move a mass from point A to point B is fixed. Energy is energy. The magnetic connection-reconnection energy has to originate with its energy source residing in the fuel. I can imagine practical advantages of one system over another like simplicity, safety, cost, etc, but I don’t see a energy advantage.

By: CMOT

CMOT — Sun, 14 Feb 2021 17:42:32 +0000

This is a very, very low thrust, very, very high efficiency drive … if it works. But if we can get this working, we can also get a lot of other drive concepts to work as well, which would probably be as good or superior to this one for practical use.

It is novel and that deserves celebrating, though …