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Huh. I don't see any obvious pitfalls here, the physics and principle of operation are quite simple. I am struggling to come up with an explanation as to why I

Huh. I don't see any obvious pitfalls here, the physics and principle of operation are quite simple. I am struggling to come up with an explanation as to why I haven't heard about this before other than sneaky DOD stuff. Who would like to bet me a large sum of money that there are currently operation military sats employing this...... EDIT: as epicureanideal pointed out, commenters in the article raised valid points discrediting most of the author's analysis. +/- charged ions get same net kick in the field, comparing proton mass to electron mass is a red herring. Overall concept still passes sniff test, just needs further analysis. It's going to be all about the angle - you need one ion species to spend more time in the field than the other to get a net thrust A magnetic scoop with a normal ion thruster might be more practical. EDIT 2: After further consideration, my concern here is what happens outside the plates. This works for infinite parallel-plate capacitors - you just need to have the field strong enough so one ion species undergoes more net acceleration. In practice the field outside the plates will not be zero and that could spoil everything EDIT 3: I know nothing. E&M is hard. There will be a current around the outside as you're pumping positive ions to one side and negative to the other. This will induce a magnetic field affecting the ions being pumped through the field. I have no clue what the net effect will be.

epicureanideal 8y ago
Some of the commenters on the linked website claim it violates physics principles. Like many people here I took several university physics courses and it seemed plausible to me, but I don't have confidence in what seems plausible to me actually working. There are a lot of "oops, I didn't think about that" types of things when making calculations in physics, from my memory... Note: After reading post by nickparker here, note that most of the commenters on the linked website who were claiming mistakes with the math seem to be wrong. Nickparker here posted links to what seem to be valid calculations showing the math works out.
- andbberger 8y ago
  For sure could be subtle crippling problems. But it passes the sniff test with flying colors
- ss2003 8y ago
  It's very good example of why we need real space testing of propulsion concepts. Once we have a bunch of engineers actually living in interplanetary space, where they can do easy experimentation, we will see some rapid developments.
  - mnl 8y ago
    Not really, actually we understand pretty well electromagnetism, electrodynamics, plasma physics and numerical methods for those. We can simulate these things, so there's no need to reinvent the wheel going full Faraday at the 21st century. A few trained physicists on Earth would do, yet people get so excited wilfully ignoring all this.
amelius 8y ago
I guess the pitfall is that it assumes the presence of a plasma, in which case the question is: can we really call it "space"? But from a practical point of view, that may not matter much, of course.
- ballenarosada 8y ago
  The presence of a very diffuse plasma in outer space is well established.

epicureanideal 8y ago

Some of the commenters on the linked website claim it violates physics principles. Like many people here I took several university physics courses and it seemed plausible to me, but I don't have confidence in what seems plausible to me actually working. There are a lot of "oops, I didn't think about that" types of things when making calculations in physics, from my memory... Note: After reading post by nickparker here, note that most of the commenters on the linked website who were claiming mistakes with the math seem to be wrong. Nickparker here posted links to what seem to be valid calculations showing the math works out.

andbberger 8y ago
For sure could be subtle crippling problems. But it passes the sniff test with flying colors
ss2003 8y ago
It's very good example of why we need real space testing of propulsion concepts. Once we have a bunch of engineers actually living in interplanetary space, where they can do easy experimentation, we will see some rapid developments.
- mnl 8y ago
  Not really, actually we understand pretty well electromagnetism, electrodynamics, plasma physics and numerical methods for those. We can simulate these things, so there's no need to reinvent the wheel going full Faraday at the 21st century. A few trained physicists on Earth would do, yet people get so excited wilfully ignoring all this.

amelius 8y ago

I guess the pitfall is that it assumes the presence of a plasma, in which case the question is: can we really call it "space"? But from a practical point of view, that may not matter much, of course.

ballenarosada 8y ago
The presence of a very diffuse plasma in outer space is well established.