The Elwing Company

[Blackjax]

I was reading the Near Earth LLC: FROM THE GROUND UP March 2012 Newsletter and saw this bit

"All-electric satellites double satellite capability or cut launch costs in half. This breakthrough caught many off guard. This technology is a factor of two improvement. Today satellites are launched with 42% spacecraft 58% fuel. In the  future that will be 83% payload and 17% fuel. This represents a huge difference in launch cost or a huge expansion on payload  capability. Boeing has a contract to build four all-electric satellites and other satellite manufacturers are making plans. The down side is 4 to 6 months to transfer a satellite to GEO. Since 80% of satellites are replacements this delay may be acceptable in many cases, although I understand Elwing has a plasma propulsion technology currently being tested at NASA that may reduce this wait to 2 - 3 months."

I'd never heard of Elwing before so I did a little digging.  They describe their technology as follows:

Based on the innovative electrode-less plasma thruster technology, Elwing product’s higher thrust and higher thrust-to-power ratio are designed to fulfill the propulsion needs of most commercial and non-commercial satellites.  The E-IMPAcT technology addresses, from a fundamental basis, the issues of grid or channel erosion, subsequent satellite contamination, high voltages, short-circuits, plume divergence or neutralizer failure and has the potential of reducing propellant mass by as much as 70%, thereby allowing satellite operators to increase the satellite payload by 50% or more.

One of the solutions identified by Elwing to these limitations is to take advantage of the ponderomotive force to produce a fully electrodeless plasma propulsion technology.  The fact that no solid part are in contact with the plasma substantially reduces the potential for erosion and spacecraft contamination, which in turn extends the thruster’s lifetime.  Furthermore, the absence of fundamental limitation on plasma density along with the possibility to independently control the density and the velocity of the plasma flow, allows for two orders of magnitude improvement in thrust density and a substantially increased thrust and thrust-to-power ratio.

Similarly, the acceleration of both ions and electrons in the same direction produce a dense, fast and focused neutral plasma beam, thereby eliminating any needs for a life-limiting neutralizer, the failure of which could leave a spacecraft crippled.  Last, the possibility to “throttle” thruster by changing not only the total power but also how a given power level is split between ionization power and acceleration power allows to change the operating point from a “High Thrust/Low Isp” mode to a “High Isp/Low Thrust” mode while maintaining acceptable efficiency.

Does anyone know anything more about them or their technology? 

I wonder if they have talked to SpaceX about partnering at all.  I could see SpaceX being more inclined to partner with a small company than with Boeing or Aerojet.

[simonbp]

If by partnering, you mean could SpaceX purchase a small electric-propulsion company like Elwing? Yes, that would make sense as a means for them to break into that market. But SpaceX in general doesn't partner if they don't have to.

[Blackjax]

If by partnering, you mean could SpaceX purchase a small electric-propulsion company like Elwing? Yes, that would make sense as a means for them to break into that market. But SpaceX in general doesn't partner if they don't have to.

I think a purchase would be one way, but comments from Elwing about being acquired seem to imply that isn't on the agenda at the moment at least with them.  SpaceX has shown a willingness to partner when a company has a strong core competency that they don't choose to, or aren't ready to, develop in house.  I'm thinking specifically of Paragon for ECLSS as an example.

If they have stated a strong interest in SEP, but we aren't seeing a hiring pattern that seems to imply in-house development, then I'd expect the next most likely thing is for them to partner for it.

Then again, the interest could be long term enough that they just aren't acting on it at all yet.

[Elmar Moelzer]

I just read about this thruster technology for the first time. Does anyone have numbers on the thrust to weight ratio, thrust to power ratio and the maximum thrust that can be generated by this type of engine?
Also wondering how it compares to an electrodeless lorentz force (ELF) thruster.

[StephenB]

A couple of interesting things from their homepage:

In addition, there is interest in electric thrusters that can operate on propellants that are storable and/or can be produced from in situ resources. E-IMPAcT’s electrodeless nature may permit it to utilize these types of resources that could quickly degrade and erode the electrodes in other electric propulsion systems. After baseline testing on standard noble gas propellants like argon and xenon, the thruster will be operated on a number of alternative propellants to gauge the performance (thrust, efficiency) on each.

Seems to be a very flexible technology.

[Elmar Moelzer]

Yeah, the ELF thruster was also tested with martian air and water among others. That is why I am wondering where they differ in performance, or if they are equal in all aspects (in which case the remaining issue would be cost).

[strangequark]

A couple of interesting things from their homepage:

In addition, there is interest in electric thrusters that can operate on propellants that are storable and/or can be produced from in situ resources. E-IMPAcT’s electrodeless nature may permit it to utilize these types of resources that could quickly degrade and erode the electrodes in other electric propulsion systems. After baseline testing on standard noble gas propellants like argon and xenon, the thruster will be operated on a number of alternative propellants to gauge the performance (thrust, efficiency) on each.

Seems to be a very flexible technology.

Most electric thrusters are pretty flexible with propellant. Hall thrusters, for instance, have been run on air, bismuth, magnesium, every noble gas, iodine, ammonia, hydrazine decomp products (someone was crazy enough to look into dual-mode chemical electrostatic), etc. It's just that given your choice, you wouldn't run off of most of those for performance reasons. This is why virtually of the electrostatic thrusters in flight service use Xenon. This tech might be able to use a little more exotic stuff (no one's tried pure oxygen, to my knowledge), but there's an associated performance hit.

[simonbp]

Hall thrusters, for instance, have been run on air, bismuth, magnesium, every noble gas, iodine, ammonia, hydrazine decomp products (someone was crazy enough to look into dual-mode chemical electrostatic), etc.

Got a reference on that? It sounds pretty cool, actually, for outer solar system non-nuclear cruise propulsion.

[A_M_Swallow]

Hall thrusters, for instance, have been run on air, bismuth, magnesium, every noble gas, iodine, ammonia, hydrazine decomp products (someone was crazy enough to look into dual-mode chemical electrostatic), etc.

Got a reference on that? It sounds pretty cool, actually, for outer solar system non-nuclear cruise propulsion.

This page shows some Hall Effect thrusters using different propellants.
http://www.busek.com/technologies__hall.htm

[strangequark]

Hall thrusters, for instance, have been run on air, bismuth, magnesium, every noble gas, iodine, ammonia, hydrazine decomp products (someone was crazy enough to look into dual-mode chemical electrostatic), etc.

Got a reference on that? It sounds pretty cool, actually, for outer solar system non-nuclear cruise propulsion.

Hmm, it was a NASA project out of Glenn I think that did the hydrazine decomp. The others are shown on the link above.

[Garrett]

Does anyone know anything more about them or their technology? 

I wonder if they have talked to SpaceX about partnering at all.  I could see SpaceX being more inclined to partner with a small company than with Boeing or Aerojet.

I doubt SpaceX will want to develop electric propulsion internally. For starters, the technology is not suitable (despite what the VASIMR folks say) for the Mars type missions that Musk envisages. There are also several companies that make reliable and proven plasma engines if they ever needed some for maintaining craft in orbit.

There's nothing really that special about the Elwing thruster from what I can see at first glance. Gridless thrusters also have disadvantages that could outweigh the advantage of less corrosion.

[Elmar Moelzer]

Gridless thrusters also have disadvantages that could outweigh the advantage of less corrosion.

What are those?

[Garrett]

Gridless thrusters also have disadvantages that could outweigh the advantage of less corrosion.

What are those?

No grids for starters. With grids you can independently pump up the voltage to an optimum value for acceleration. Without grids (Hall thrusters, VASIMR, etc.) your acceleration voltages are coupled to your plasma parameters, which may or may not be a good thing.

I'm not against gridless technology (am a big fan of Hall thrusters) but I'm just pointing out that grids aren't going away any time soon. I have colleagues across France who are working on both grided and gridless thruster technology.