Neumann Drive: A Pulsed Cathodic Arc Thruster for Spacecrafts

>Anyone know how the mass stacks up though?

I haven't been able to find that yet, but even if significantly worse this may still have an important big upcoming space. In the upcoming Starship era, economics is going to play a historically huge new role in space, just as it does in Starship itself where many of the design and material decisions are optimized around cost and simplicity, even at some performance penalty, vs the old space total focus on perf. A drive that performs worse, but is much easier and cheap, could be useful alongside the others in some roles when you can throw 100+ tons at a problem at <$200/kg to LEO, or even <$100/kg.

Good data sheet!

I wonder where it fits on this table: https://en.wikipedia.org/wiki/Spacecraft_propulsion#Table_of...

Also looked at this table: https://en.wikipedia.org/wiki/Ion_thruster#Comparisons

The weight on this one looks really good, not even counting the lack of propellant. I'm going to guess that has a downside, that the total impulse is limited by how small the fuel rod is.

> That looks awesome!

"Power overwhelming" comes to mind

I would note that delta v from LEO to mars orbit is 7500m/s, which would only need ~40kg of fuel from your calculations (didn’t recalculate with additional fuel mass, ymmv). That doesn’t seem outrageous.

>up to 250kNs of total impulse and a wet mass of 10-20kg

The specific impulse here is 3-6 times better than the one of chemical. Considering the existing tech the solar+ionic seems to be the best option for going to Mars. With some very feasible development of existing tech the nuclear+ionic seems to be the best for farther into Solar and beyond (if I didn't make large mistakes https://news.ycombinator.com/item?id=38445404)

  > For ND-500+, they claim up to 250kNs of total impulse and a wet mass of 10-20kg

Wouldn't bet on it.

The same PDF on their website[0] claims an Isp of 2500 seconds. If you do the math (I=mv), the propellant mass works out to 10.2 kg. So at the low end of their "10-20 kg" estimate, 102% of the total thruster mass would need to be the eroded solid propellant, leaving a -2% mass budget left over to cover the power supply, capacitors, control electronics, and all non-eroded structures.

That seems... optimistic.

The technology seems cool, but putting trivially impossible numbers on your launch website is a big red flag.

[0] https://web.archive.org/web/20231221000314/https://neumannsp...

That looks like it, I take it the "solid state" aspect of using a metal rod as the source of material to ionize is the main claim to fame here. It does mean 'refueling' is easy, just pop another rod in (easy if you happen to in orbit nearby, that is). The suggestion that you could make new rods from asteroids etc. is cool, but there's quite a gap between theory and practice still...

It's like an ion drive. Here's the steps:

1. Start with a metal rod.

2. Remove one atom from the rod.

3. Remove electron from atom.

4. Now that the atom is charged, shoot it out the back of the engine really fast using electrical repulsion.

5. Shoot the electron out the back (using a different pipe) so that the exhaust doesn't come back at you due to electrostatic attraction.

6. Now you have the rod, with one less atom. Repeat. A whole ton of times.

Steps 2&3 might happen simultaneously, not entirely sure the mechanism but generally an electrical arc is violent, it will spallate and ionize a few atoms here and there.

Not having a tank is huge, and the first ionization energy of many metal ions is far far lower than noble gases, which are what is commonly used in normal ion drives

Yeah they'll use a capacitor to charge up and then dump high current quickly (that's what they're good at, as opposed to batteries which are better suited for a longer, steadier, lower current output).

How is this ‘really cool’?

It messed up and didn’t give you an answer and you have no way of knowing if the information you ‘learned’ is true if you don’t already understand ISP etc.

I mean wolfram alpha would give you the answer immediately without all the bullshit conversation.

It’s so weird to me how this glorified ELIZA has people so keen to tell us what GPT said in every single thread.

Maybe it's harder to strip atoms from a lead cathode, and/or harder to strip one of its electrons?

Density doesn’t mean anything at the ion level. Yes, lead has a higher atomic mass, but at the end of the day it’s about momentum and energy. If they can shoot a Mo2+ out twice as fast as Pb2+, it’s about them same.

Lead is hazardous which is something the marketing material explicitly avoids.

Mitigating factor is that the outbound craft exhaust functions as an AM radio. Admittedly modulation is slow, around 6Hz according to one data-sheet, but also quite energetic and directed.

Hit the reader mode button in the address bar? All the info’s there in Firefox at least. Safari seems to have trouble with it.