thread for segments files and parameters for simulation runs

[icarus]

happyjack:

Remember, no-one really knows how it 'should' work, that's why they are building experiments, not commercial reactors.

[happyjack27]

Ah, I see why you have two WBs. But I'm 99.9% certain you're only supposed to have an electron WB.

The ions should be confined by the electrons, not by the magnetic field. But it makes sense you would get that without the e-field on. Had me worried there

the efield is on in the later sims. it's only in the spikey WB electron only sims that it's off. but for the time being i'm modelling my static efield as if the wires were infinite because i don't think the results of the finite wire calculations are correct. (and that's why i had them off then.) so that might affect things.

at high enough field strengths, i don't see why you wouldn't get ions contained by the mag field too, if at a much larger radius. anycase i'll run some ion-only sims to verify it's not related to the electrons.

i'm running 3m radius at around 2million amp-turns and 10^-8 coloumbs per meter charge on the magrid. i'm hoping that's in the right ballpark?

i only have 14k particles to play with, so with 1 modeled ion/electron per particle that's very low space charge. but i can turn up the ratio to approximate higher space charges. (particles will see themselves as 1 particle but each other as multiple particles)

[happyjack27]

3-D Particle-in-cell is extremely expensive. Resolution goes like (N)**.5 where N is the number of particles. You have multiple timescales and multiple spatial scales to resolve. This means supercomputers.

compared to 20 years ago my cellphone is a supercomputer.

also, this is on a gpgpu, which compared to today's computers is like a supercomputer for certain types of problems, 3-D Particle-in-cell simulations being one of them.

[happyjack27]

Again, it's the top of their hill. They do not sit there, it's just their average position. They are going to come down, they are going to thermalize.

but it's not like there's nothing keeping them there. i mean if you were just going to shoot electrons into one spot and hope they don't repel each other too fast, then why bother building the darn coils?

[icarus]

dave:

Again, it's the top of their hill. They do not sit there, it's just their average position. They are going to come down, they are going to thermalize.

Pure conjecture. What hill are you babbling about by the way? At the center of a hollow charged sphere there is zero potential .... now add in a much smaller, flexible concentric sphere of opposite charge bound by magnetic fields what happens to your precious "hill"?

Btw, you are using "thermalize" in two different, conflicting ways. It is possible to have cold thermalized electrons and hot thermalized electrons ... so what are you talking about?

[TallDave]

Again, it's the top of their hill. They do not sit there, it's just their average position. They are going to come down, they are going to thermalize.

but it's not like there's nothing keeping them there. i mean if you were just going to shoot electrons into one spot and hope they don't repel each other too fast, then why bother building the darn coils?

No, there really is nothing keeping them there. The coils don't keep them in the center of the WB, they just keep them in the WB.

[TallDave]

dave:

Again, it's the top of their hill. They do not sit there, it's just their average position. They are going to come down, they are going to thermalize.

Pure conjecture. What hill are you babbling about by the way? At the center of a hollow charged sphere there is zero potential .... now add in a much smaller, flexible concentric sphere of opposite charge bound by magnetic fields what happens to your precious "hill"?

Btw, you are using "thermalize" in two different, conflicting ways. It is possible to have cold thermalized electrons and hot thermalized electrons ... so what are you talking about?

What?? You do accept there's a potential well and an anode, nonspherical Magrid, right? Or are you arguing against the existence of IEC devices? Very odd.

The question was "why does thermalization mean the system needs to be driven?" The answer is, because electrons will tend thermalize to low potential and low energy. This is bad, for the aforementioned reasons. Upscattered electrons will tend to make it out the cusps and to the wall, which isn't as bad because they're climbing another hill to get there, and thus not taking as much energy with them.

[TallDave]

3-D Particle-in-cell is extremely expensive. Resolution goes like (N)**.5 where N is the number of particles. You have multiple timescales and multiple spatial scales to resolve. This means supercomputers.

compared to 20 years ago my cellphone is a supercomputer.

also, this is on a gpgpu, which compared to today's computers is like a supercomputer for certain types of problems, 3-D Particle-in-cell simulations being one of them.

Unforunately, he wrote that a year ago. But I have high hopes for the future.

[TallDave]

happyjack:

Remember, no-one really knows how it 'should' work, that's why they are building experiments, not commercial reactors.

Yes, but we do have some idea how the experiments "should" work, and what a model of the experiments "should" look like.

[TallDave]

at high enough field strengths, i don't see why you wouldn't get ions contained by the mag field too, if at a much larger radius. anycase i'll run some ion-only sims to verify it's not related to the electrons.

You would get some significant confinement at reactor sizes, as Rick has alluded to. But ion pressure should be low due to the well (i.e. IEC). That's why when Rick did his ITER comparison he ignored it in the beta=1 density calculation, to Art's confusion. So I'd be a bit surprised to see them in a shell outside the electrons.

[icarus]

Yes, but we do have some idea how the experiments "should" work,

speak for yourself einstein, you do know that mother nature will make you look like a complete idiot when/if it is ever known how this thing behaves?

You are definitely not a physicist to be so categorically cock-sure of how this thing will work .... but enough of that, just stop putting unsupported conjecture into a theory section please, for once.???

[happyjack27]

No, there really is nothing keeping them there. The coils don't keep them in the center of the WB, they just keep them in the WB.

that's what i mean. i don't mean the exact center. in fact from my sims it looks like the WB is pretty hollow. i'd imagine due to mutual electrostatic repulsion.

[happyjack27]

at high enough field strengths, i don't see why you wouldn't get ions contained by the mag field too, if at a much larger radius. anycase i'll run some ion-only sims to verify it's not related to the electrons.

You would get some significant confinement at reactor sizes, as Rick has alluded to. But ion pressure should be low due to the well (i.e. IEC). That's why when Rick did his ITER comparison he ignored it in the beta=1 density calculation, to Art's confusion. So I'd be a bit surprised to see them in a shell outside the electrons.

these are in sims w/ 3m coil radius. which i understand are "reactor sizes".

[krenshala]

you can see the electrons are much denser in the center, and given how they accumulated, that can only imply that their lifetimes are much longer.

Accumulation at the center will happen naturally, because it's where they're slowest. That's why there's a virtual cathode.

so really how many electrons do you want to pump in to the system?

Enough to replace the ones that thermalize.

i thought electron losses where the biggest problem.

Not really, PWs are e-driven by design. Excess electron losses would be a problem.

Electrons in the middle will head down their potential hill, and then they're going to bounce around randomly and thermalize. You might increase their confinement time by aiming for the middle (which is why I say it's interesting), but again I think aiming for the center means your well potential is dropping over time.

In one of the videos I noticed the B (e ?) field was blocking the e-guns. On some of the views, however, I noticed that even then the occasional electron was making it through the magrid and into the wiffleball/well. I wasn't able to tell from the video if electrons were making it back out, however, and wasn't able to really check as work intruded.

What I think would be an interested thing to check, and I believe would help with what you guys are talking about above, would be to start the sim with zero electrons "in the system" and the magrid active, then power up the e-guns and slowly start shooting electrons into the well.

This should test both whether you can get enough electrons into the system with the guns outside the magrid (firing into/through cusps), but it should also be another good way to verify whether they will spontaneously form that electron shell/sphere near the center.

Now if only I had a better video card to run some of these myself ... Did you ever post up the exe for it? My system may be slow, but I can always kick stuff off and check it after waking up/getting back from work.

[happyjack27]

Yes, but we do have some idea how the experiments "should" work,

speak for yourself einstein, you do know that mother nature will make you look like a complete idiot when/if it is ever known how this thing behaves?

You are definitely not a physicist to be so categorically cock-sure of how this thing will work .... but enough of that, just stop putting unsupported conjecture into a theory section please, for once.???

whoa, settle down there! i'm much enjoying my discussion w/TallDave. and i'm in fact quite interested in how it "should" work.