Fusion with space related aspects thread

[LMT]

Moderator:
LMT, I don't know if you realize it, but some of your posts veer into un-civil discourse: passive-aggressive attacks on other members.  I note your recently deleted posts.

You also sometimes seem not to listen well to those discussing with you.

My own observation:  You've got a long string of shout-down posts on these topics, many delivered in bad faith, all pretty clearly incorrect.  Many NSF posters do get shouty, when unfamiliar material pops up.  But instead of shouting, those posters could "be more excellent", and read. 

[lamontagne]

You might trace neutrons through Winterberg's professional appendices, and report back.

Goodness, LMT, Why should I? I already know the answer, you're the one proposing that these designs can work an be essentially aneutronic, not me.  And a link to a table of contents is not that informative a source.

Sorry everyone to be generating so much noise, pehaps I should just give up on this.

No, I think you don't know.  I linked the appendices directly there, giving you just what you asked for.  Read that to learn how his autocatalytic innovation leverages the various 3F neutron sources.  Then summarize the neutron trace in post, fairly.

As for "essentially aneutronic", you do want some thermal neutrons in the reflector backing -- to breed self-sufficient tritium.  Some materials and parameters for that practical adaptation were noted.  1 2

OK.  It's going to be heavy going  and I have other priorities, but I will go down that rabbit hole for a while and see where it gets me.  I am looking for the absorption of high energy D-T in the fusion reaction and how many values are measured/calculated vs the ones that are hand waved in to get things to work, as in the later thermal paper.  The paper proposes at least 4 methods to get to the gains Winterberg is hoping for, so there is a lot of unpacking to do.  This is very similar to Thio's work using plasma guns, and I have access to some work that was done in the Icarus project to review Daedalus, so that should be a help.  I will try to report from time to time on my progress.  Wish me luck!
The paper is joined.

[LMT]

I linked the appendices directly there, giving you just what you asked for.  Read that to learn how his autocatalytic innovation leverages the various 3F neutron sources.  Then summarize the neutron trace in post, fairly.

It's going to be heavy going...

This is very similar to Thio's work using plasma guns...

It is not very similar to plasma jet magneto-inertial experiments.  The appendices explain a spherical implosion design with similarities to Mike Shot and other old DoD devices.  Focus on what's explained and remember DoD device history.

Appendix A:  Implosion of a Compressible Spherical Shell
Appendix B:  Generation of Intense Black Body Radiation through High-Velocity Impact
Appendix C:  Autocatalytic Fission-Fusion Implosions
Appendix D:  Fission-Fusion Chain Reactions

[lamontagne]

Phase 1 of the Winterberg analysis.

It's only very accessorily a propulsion paper.  It's really a paper about a very small nuclear device, that can have many uses.  Winterberg covers many domains and has many papers so I need to be careful to stick to the point.

The core of the paper describes the device, a very small nuclear bomb.  The compression method proposed allows for a much smaller critical mass, as the compression scheme condenses the plutonium/uranium 235 into a dense mass that can self ignite more easily, and the DT layer creates neutrons that increase the reaction, as in the original bomb.

The compression is a dual layer liner mechanism, explosively compressed.  A bit like the J. Slough compressed metal liner devices.

The description is coherent and simple.  The appendixes have all the meat.  The main handwaved element at this point is the 10% burn up fraction, that I hope is justified in the appendixes.

There are two layers of uranium and beryllium, that are nice and thick, thicker than the mean free path of the 14 MeV neutron, so indeed most of them will be absorbed.  I have a table of mean free paths that I made a decade ago, but I need to rebuild it as it holds only the values and not the actual math, that I have lost.  I aim to find out how many neutrons get out, if any.

It's a form of suitcase nuke, but fortunately not too incredibly powerful.  My next question is how do we calculate that 10% gain?

BTW, the fusion aspect seems to add nothing to the gain, or very little.  It helps the gain to happen, but this is essentially powered by fission, not fusion.  I will try to see what this means on a larger scale for a ICF one hz vehicle.  But in the long run it will be interesting to compare to a 25% burn up fraction NEP engine, operating in the high temperatures.

Joined spreadsheet, the next version will probably take more time as I go through the math.

I've included a very simple model of the Ivy Mike bomb using the general information on the Web.  I still need to calculate the burn up fraction of the fission part, and of course my fusion part is probably too simplisitic.

[LMT]

the fusion aspect seems to add nothing to the gain, or very little.  It helps the gain to happen, but this is essentially powered by fission, not fusion.

Posters might wonder at that. 

Effective neutron multiplication factor (v*) is vital here.  See eq. (D.16), where he applies the fusion coupling ratio (f) to boost v* output. 

By itself, a 235U fissile core has v of 2.5.  With Winterberg 3F, v* jumps, as with his example v* of 12.8.

That's an extraordinary result, for a fissile core that can mass < 1 gram.

[zubenelgenubi]

Moderator:
LMT, I don't know if you realize it, but some of your posts veer into un-civil discourse: passive-aggressive attacks on other members.  I note your recently deleted posts.

You also sometimes seem not to listen well to those discussing with you.

My own observation:  You've got a long string of shout-down posts on these topics, many delivered in bad faith, all pretty clearly incorrect.  Many NSF posters do get shouty, when unfamiliar material pops up.  But instead of shouting, those posters could "be more excellent", and read.

Moderator:
Again, you are not listening.

So, I will state myself even more clearly.

Post civilly, or lose your posts.

[Asteroza]

I'm pushing my luck here, but there's an outfit claiming anuetronic fusion in their borated water plasma electric thruster is yielding a 50% thrust improvement over basic water plasma.

https://rocketstar.nyc/

[edzieba]

I'm pushing my luck here, but there's an outfit claiming anuetronic fusion in their borated water plasma electric thruster is yielding a 50% thrust improvement over basic water plasma.

https://rocketstar.nyc/

From their press release:

The base thruster generates highspeed protons through the ionization of water vapor. When these protons collide with the nucleus of a boron atom, the atom undergoes fusion

So the main question is: does arc heating of a water plasma actually generate protons of sufficiently high energy for p-B fusion in the first place? 
On the upside:

The fusion discovery was first made during an SBIR Phase 1 for AFWERX where boronated water was introduced into the pulsed plasma thruster’s exhaust plume. This created alpha particles and gamma rays, clear indications of nuclear fusion. It was further validated during the subsequent SBIR Phase 2, where at Georgia Tech's High Power Electric Propulsion Laboratory (HPEPL) in Atlanta, Georgia it not only created the ionizing radiation but also improved the base propulsion unit’s thrust by 50%.

Independant testing is good. Publishing the results of that testing would be even better.

And I'll get in the obligatory "Zip Fuels, but with fusion this time!".

[lamontagne]

Phase II of the Winterberg analysis

Corrected some density mistakes in my own calculations and found added structural detail in the text.

Got to Appendix B and have hit a snag.

The problem is simple.  In the statement of the problem Winterberg says that the expected velocity of the outer aluminum shell is 5 km/s after the explosion.  However, in appendix B he uses a velocity of 50 km/s to calculate the net gain of the vaporization of the second wall.

The weight of the first aluminum wall is almost exactly 1 kg.  At 5 km/s this is about 13 MJ, which seems, intuitively, to be a reasonable fraction of the original 40 MJ of explosive.  However at 50 km/s this becomes 1 300 MJ, which is  32 times the energy of the explosive, and of course, impossible.

So, due to this, the temperature reached according to Appendix B is about 170 times less with 5 km/s than 50 km/s.  At two orders of magnitude less, I don't think the rest will work.  However, I guess I will push on and see where this goes.

Again, these may just be typos.  Need to check the whole thing.

[Coastal Ron]

Real world fusion space engine, not some paper study:

Fusion drive space engine ready for flight - New Atlas

Relevant quote:

What RocketStar is doing with its version of aneutronic nuclear fusion is using water for the propellant for its M1.5 FireStar Drive, which is a nuclear fusion-enhanced pulsed plasma thruster. It uses water for its propellant that's been laced with boron.

An example of technology that is "near-term", especially since it will be launching to space later this year on the ION Satellite Carrier, a proprietary orbital transfer vehicle operated by D-Orbit.

This is a small version, but likely can be scaled up over time. Technology readiness level (TRL) 6, and later this year it could be TRL 7.

[RON_P]

Lockheed Martin Ventures invests in Helicity Space
https://spacenews.com/lockheed-martin-ventures-invests-in-helicity-space/

SAN FRANCISCO – Helicity Space, a California startup developing fusion engines for spaceflight, announced an investment April 2 from Lockheed Martin Ventures.

While the parties declined to reveal the value of the investment, Lockheed Martin’s backing is important because it’s one of the “strategic partners that will matter over the next 10 years,” Helicity co-founder Stephane Lintner told SpaceNews.

Other strategic partners include Airbus Ventures and Voyager Space Holdings, two of the investors in Helicity’s seed funding round announced in December.

Deep Space
Pasadena-based Helicity is developing technology to propel spacecraft with short bursts of fusion.

“Propulsion is the biggest problem we have right now” for deep space travel, Lintner said. “Fusion brings the promise of very little propellant, very high power and potentially covering very long distances.”

Another approach to speeding up deep-space transportation is nuclear thermal propulsion, which Lockheed Martin is exploring under an agreement with NASA and the Defense Research Projects Agency.

“As we look towards the future of travel beyond the moon, other methods of propulsion need to be undertaken,” said Chris Moran, Lockheed Martin Ventures vice president and general manager. “A nine-month or one-year trip to Mars is quite long. If you want to go beyond Mars, the mission will be dominated by the mass of the propellants.”

As a result, Lockheed Martin sees potential in Helicity’s plasma fusion approach.

Four Guns
“Many things need to be worked out but they’re at an interesting phase,” Moran said. “They are combining plasma guns to create an intense plasma with the level of heating that’s required to create a fusion-type result. They’ve done it with two guns.”

Lockheed Martin Ventures and other investors are providing funding for Helicity to continue testing with four plasma guns.

“The hope is that they can retire a certain degree of risk to allow us all to see whether this is a practical approach or not,” Moran said. The testing also may provide information on “the levels of thrust that can be created. Once we understand that, then we get a good understanding of the future work that needs to be done.”

Helicity sees Lockheed Martin as a potential long-term customer and as a strategic partners who could offer guidance in navigating the defense sector and attracting government support.

Plus, Lockheed Martin Ventures’ backing “indicates that the field is maturing” and lends credibility to Helicity’s technology because of the due diligence that proceeded the investment, Lintner said.

Lockheed Martin Ventures usually invests between $1 million and $5 million in early-stage companies developing “disruptive, cutting edge” technologies in the defense giant’s current markets or new areas of interest. Space companies in the Lockheed Martin Ventures portfolio include ABL, Agile Space Industries, Elve, HawkEye 360, Hedron, Orbit Fab, Rocket Lab, Satellite Vu, Slingshot Aerospace, Terran Orbital and Xona Space Systems.

[LMT]

Phase II of the Winterberg analysis...

The weight of the first aluminum wall is almost exactly 1 kg.  At 5 km/s this is about 13 MJ, which seems, intuitively, to be a reasonable fraction of the original 40 MJ of explosive.  However at 50 km/s this becomes 1 300 MJ, which is  32 times the energy of the explosive, and of course, impossible.

No, it’s 13.5 grams, from explicit dimensions.  It works.

Winterberg 2004 is the analysis; we can apply those numbers.

[lamontagne]

Phase II of the Winterberg analysis...

The weight of the first aluminum wall is almost exactly 1 kg.  At 5 km/s this is about 13 MJ, which seems, intuitively, to be a reasonable fraction of the original 40 MJ of explosive.  However at 50 km/s this becomes 1 300 MJ, which is  32 times the energy of the explosive, and of course, impossible.

No, it’s 13.5 grams, from explicit dimensions.  It works.

Winterberg 2004 is the analysis; we can apply those numbers.

13.5g is the weight of the second wall.  This works if all the energy from the first wall is transfered to the second wall. 
The mass of the first wall is 1kg and it moves initially at 5 km/s for 13 MJ.
The mass of the second wall is 13.5g and it moves at 50 km/s for 17 MJ. that's a bit more, but it can be attirbuted to rounding.
The mass of the third wall made from uranium and should be is 3,3g according to dimensions in the paper.  However,  If it moves at 200 km/s, that's about 66 MJ, so that's too fast.  Supposing it is moving at 200 km/s, then the mass of uranium is  0,0086g ot less.

[LMT]

Phase II of the Winterberg analysis...

The weight of the first aluminum wall is almost exactly 1 kg.  At 5 km/s this is about 13 MJ, which seems, intuitively, to be a reasonable fraction of the original 40 MJ of explosive.  However at 50 km/s this becomes 1 300 MJ, which is  32 times the energy of the explosive, and of course, impossible.

No, it’s 13.5 grams, from explicit dimensions.  It works.

Winterberg 2004 is the analysis; we can apply those numbers.

The mass of the first wall is 1kg...

No, it has "the same thickness" at r2 = 1 cm; hence, 13.5 grams. 

3F is best-in-class.  If a 3F D-T hybrid drive bred its own tritium, inefficient D-D or D-3He drive designs couldn't compete.  Moving forward, the thread might explore 3F and tritium breeding.

[lamontagne]

Phase II of the Winterberg analysis...

The weight of the first aluminum wall is almost exactly 1 kg.  At 5 km/s this is about 13 MJ, which seems, intuitively, to be a reasonable fraction of the original 40 MJ of explosive.  However at 50 km/s this becomes 1 300 MJ, which is  32 times the energy of the explosive, and of course, impossible.

No, it’s 13.5 grams, from explicit dimensions.  It works.

Winterberg 2004 is the analysis; we can apply those numbers.

The mass of the first wall is 1kg...

No, it has "the same thickness" at r2 = 1 cm; hence, 13.5 grams. 

3F is best-in-class.  If a 3F DT hybrid drive bred its own tritium, inefficient D-D or D-3He drive designs couldn't compete.  Moving forward, the thread might explore 3F and tritium breeding.

Depends what we call the first wall, perhaps?  Clearly the outside wall, that I call the first wall, is much heavier than the second wall if it has the same thickness, since it has ten times the radius.  This only works if the inner wall is 32 grams and all the energy from the outer wall is transfered to the inner wall.  Like a pair of billard balls.

The dimensions for the third wall, made of uranium, are incompatible with the stated velocities.

This is not a fusion engine.  It's a fission engine with some fusion enhancement.  And I don't see how it can work with the dimensions given.  Not that it matters in any way, since I don't see why it would ever be built, and would be very expensive to operate.  Haven't calculated that part yet, however.

[LMT]

Phase II of the Winterberg analysis...

The weight of the first aluminum wall is almost exactly 1 kg.  At 5 km/s this is about 13 MJ, which seems, intuitively, to be a reasonable fraction of the original 40 MJ of explosive.  However at 50 km/s this becomes 1 300 MJ, which is  32 times the energy of the explosive, and of course, impossible.

No, it’s 13.5 grams, from explicit dimensions.  It works.

Winterberg 2004 is the analysis; we can apply those numbers.

The mass of the first wall is 1kg...

No, it has "the same thickness" at r2 = 1 cm; hence, 13.5 grams. 

3F is best-in-class.  If a 3F DT hybrid drive bred its own tritium, inefficient D-D or D-3He drive designs couldn't compete.  Moving forward, the thread might explore 3F and tritium breeding.

Clearly the outside wall, that I call the first wall, is much heavier than the second wall if it has the same thickness, since it has ten times the radius. 

No, Appendix B is clear.  It's "the same thickness" at r2, specifically, so that "half of the kinetic energy is converted into heat", giving radiation "sufficient to ablatively implode a capsule".  There's no real issue.  Practical benefits and explorations suggest themselves.

[lamontagne]

Phase II of the Winterberg analysis...

The weight of the first aluminum wall is almost exactly 1 kg.  At 5 km/s this is about 13 MJ, which seems, intuitively, to be a reasonable fraction of the original 40 MJ of explosive.  However at 50 km/s this becomes 1 300 MJ, which is  32 times the energy of the explosive, and of course, impossible.

No, it’s 13.5 grams, from explicit dimensions.  It works.

Winterberg 2004 is the analysis; we can apply those numbers.

The mass of the first wall is 1kg...

No, it has "the same thickness" at r2 = 1 cm; hence, 13.5 grams. 

3F is best-in-class.  If a 3F DT hybrid drive bred its own tritium, inefficient D-D or D-3He drive designs couldn't compete.  Moving forward, the thread might explore 3F and tritium breeding.

Clearly the outside wall, that I call the first wall, is much heavier than the second wall if it has the same thickness, since it has ten times the radius. 

No, Appendix B is clear.  It's "the same thickness" at r2, specifically, so that "half of the kinetic energy is converted into heat", giving radiation "sufficient to ablatively implode a capsule".  There's no real issue.  Practical benefits and explorations suggest themselves.

Ah, I just though that perhaps he's starting with a very thin at 10 cm wall and compressing it down to 3mm thick when it hits the other 3 cm thick wall.  That might work.  I'll look into it. So the first wall has two thicknesses, one at To and another at T1

[LMT]

...perhaps he's starting with a very thin at 10 cm wall and compressing it down to 3mm thick...

It's implosion.

Not that it matters in any way, since I don't see why it would ever be built, and would be very expensive to operate.  Haven't calculated that part yet, however.

You might calculate the 3F neutron trace first.  "I already know the answer," you said, but your spreadsheet disagrees.

-

Given ISRU methalox and tritium breeding, and the drive's extraordinary specific energy, 3F / MOX tug operation shouldn't be expensive.  It's much like conventional Starship tanker operation -- in orbit, only, without a tanker's launch and landing cycles. 

And Starship tankers aren't too expensive to "ever be built".

[lamontagne]

...perhaps he's starting with a very thin at 10 cm wall and compressing it down to 3mm thick...

It's implosion.

Not that it matters in any way, since I don't see why it would ever be built, and would be very expensive to operate.  Haven't calculated that part yet, however.

You might calculate the 3F neutron trace first.  "I already know the answer," you said, but your spreadsheet disagrees.

-

Given ISRU methalox and tritium breeding, and the drive's extraordinary specific energy, 3F / MOX tug operation shouldn't be expensive.  It's much like conventional Starship tanker operation -- in orbit, only, without a tanker's launch and landing cycles. 

And Starship tankers aren't too expensive to "ever be built".

Haven't reached the neutrons yet.  Still trying to understand the container.
Thanks to you pointing it out, I understand that the outer aluminum shell has to mass 32 grams.  however, at 20 cm diameter, that means the aluminum is 0,4mm thick, about twice the thickness of heavy aluminum foil.
The device holds a vacuum, and I don't see how it could be structurally functional at that thickness.  So I guess it would have to be the explosive itself that serves as structural material?  I don't know anything about the structural strength of explosives, but i guess it would have to be pretty rigid. 
Alternatively, there might be an outer structural shell, not described in the paper. How to prevent that outer layer from destroying whatever contains the explosion? If it's instantly ionized then you might use magnetic containment but if it remains structurally intact, then it's going to damage the containment?
And how is the central 1 cm ball suspended exactly in the center of the sphere?  Could be wires, but won't these introduce perturbations in the explosion and reduce the efficiency of the energy transfer between the layers?
Anyway, I guess I need more study before I believe that this can be a practical power source and start designing anything on its basis.

[LMT]

how is the central 1 cm ball suspended...

Simple container options are OT.

Not that it matters in any way, since I don't see why it would ever be built, and would be very expensive to operate. 

Anyway, I guess I need more study before I believe that this can be a practical power source and start designing anything on its basis.

3F has DoD heritage and economical options.  Cf. DD fusion concepts like Icarus Firefly.  Such drives wouldn't be competitive in the solar system, due to low specific energy.  To achieve useful in-system thrust, immense drives and immense propellant loads would be needed, impractically. 

In your enthusiastic 2020 report, you accepted a Firefly's 16,611 t deuterium propellant load, but omitted its cost:  ~ a quarter of a trillion dollars.  Such an immense and simple cost should be included in a BIS report.