Spheroidal Foci and POPS?

blaisepascal · Post by **blaisepascal** » Sat Oct 17, 2009 8:33 pm

BenTC wrote:Just speculating...
octopus = octopi
focus = foci (foe-kie)
:] bigger grin

The two proper plurals for octopus are either "octopusses" or "octopodes". The word is of greek origin, not latin.

alexjrgreen · Post by **alexjrgreen** » Sun Oct 18, 2009 1:26 pm

blaisepascal wrote:
BenTC wrote:Just speculating...
octopus = octopi
focus = foci (foe-kie)
:] bigger grin
The two proper plurals for octopus are either "octopusses" or "octopodes". The word is of greek origin, not latin.

What are the plurals of 'octopus', 'hippopotamus', 'syllabus'?

DeltaV · Post by **DeltaV** » Mon Oct 19, 2009 6:14 am

"Shed-yool", "Sked-jool", whatever...

Another possible application for spheroidal Polywell fields:

http://forum.nasaspaceflight.com/index. ... =13020.630
Star-Drive, Reply #637 (Paul March, Mach-Lorentz Thruster investigator):

"...Seriously, using a WB-XX reactor as our starting point, we have the required energy source that we could then modulate its output (d^2E/dt^2) by applying a time varying E-field to the already existing 100kV E-field potential well used to retard and covert the kinetic energy of the escaping fusion helium ions into electrical potential energy for the ship. If we then bulk accelerated the fusion core plasma and these escaping helium ions at the appropriate MLT’s 2X the E-field rate by differentially modulating the existing B-field virtual grid coils in a particular direction, we could have one hell of a dual use technology with full 360 degree thrust vectoring in the X, Y, and Z axes!!"

Hmmmm...

MSimon · Post by **MSimon** » Mon Oct 19, 2009 8:49 am

I'm still sceptical of the tit bits.

chrismb · Post by **chrismb** » Mon Oct 19, 2009 9:18 am

Show me a steady trickle of neutrons out of a Polywell first, then we can tinker and tune, and I'll join in with the fantasies!

D Tibbets · Post by **D Tibbets** » Mon Oct 19, 2009 6:40 pm

DeltaV wrote:"Shed-yool", "Sked-jool", whatever...

Another possible application for spheroidal Polywell fields:

http://forum.nasaspaceflight.com/index. ... =13020.630
Star-Drive, Reply #637 (Paul March, Mach-Lorentz Thruster investigator):

"...Seriously, using a WB-XX reactor as our starting point, we have the required energy source that we could then modulate its output (d^2E/dt^2) by applying a time varying E-field to the already existing 100kV E-field potential well used to retard and covert the kinetic energy of the escaping fusion helium ions into electrical potential energy for the ship. If we then bulk accelerated the fusion core plasma and these escaping helium ions at the appropriate MLT’s 2X the E-field rate by differentially modulating the existing B-field virtual grid coils in a particular direction, we could have one hell of a dual use technology with full 360 degree thrust vectoring in the X, Y, and Z axes!!"

Hmmmm...

I'm not sure direct thrust could be implimented primarily through one cusp by varying megnetic and/ or electrical fields without severly compromising the quasispherical shape and thus efficiency of the wiffle ball. The alphas and other charged fusion products will apparently leave though all of the cusps naturally. Increasing preferences for peticular cusps might be doable so long as a tolorable decrease in efficiency can be maintained. I don't know how much stearage of the exaust plumes could be done with magnetic nozzels. Perhaps the fusion ions exiting through the 'forward' cusps could be utilized for power conversion- to provide ship power, recycled reactor power, and possibly power for a realativistic electron beam; while the rearward facing cusps feed magnetic nozzles for direct or dilluted thrust. Would this be a synergistic combination of both drive types- or a bad compromise of both drive types?

Dan Tibbets

DeltaV · Post by **DeltaV** » Tue Oct 20, 2009 1:26 am

I'm thinking that all of the alphas (ideally) would eventually get used for direct power conversion, after doing Mach-Lorentz-Woodward thrust duty, but not for "classical" thrust. Assuming both devices (Polywell and MLT) are separately shown to work as desired, then for a Polywell/MLT combo some kind of asymmetry would need to be introduced during each mass oscillation cycle to obtain thrust in a particular direction. To get the required asymmetry, maybe different voltages could be applied to individual magrid coil casings while the coil currents are being tweaked for spherical or spheroidal magnetic field oscillation. The inter-coil nubs would then need to be insulators, with extra wiring needed, or maybe radially-aligned coil supports with no inter-coil nubs at all could be used. Correct timing/phasing would be extremely critical. Sealing the unit would allow operation in air or underwater instead of only in space (USAF? USN? NASA? $$?).

Aero · Post by **Aero** » Tue Oct 20, 2009 2:01 am

while the coil currents are being tweaked for spherical or spheroidal magnetic field oscillation.

I have an observation not specific to this thread, because several posts in several different threads have included comments similar to the above quote. I was (and still am) under the impression that superconducting magnets do not permit rapid fluctuation of the coil current. Are we expecting that we will be using copper coils, or am I wrong and the current in superconducting coils can be oscillated at reasonably high frequency?

DeltaV · Post by **DeltaV** » Tue Oct 20, 2009 2:13 am

Graphene, with unspecified dopants.

DeltaV · Post by **DeltaV** » Tue Oct 20, 2009 2:47 am

This is scary. My previous post was intended to be comical. Then I found this:

http://arxiv.org/PS_cache/arxiv/pdf/070 ... 3115v1.pdf

D Tibbets · Post by **D Tibbets** » Tue Oct 20, 2009 9:19 pm

Aero wrote:
while the coil currents are being tweaked for spherical or spheroidal magnetic field oscillation.
I have an observation not specific to this thread, because several posts in several different threads have included comments similar to the above quote. I was (and still am) under the impression that superconducting magnets do not permit rapid fluctuation of the coil current. Are we expecting that we will be using copper coils, or am I wrong and the current in superconducting coils can be oscillated at reasonably high frequency?

When I make blanket statements about varing the electromagnetic fields, ion/ electron densitiy variations in volume and time space (?), I'm assuming knobs exist, despite my ignorance. I suspect your view on supermagnets are acurate. Copper coils could make up the main magnets, or be a suplimental magnet to quicky vary the overall magnetic field. Also any variation in the electron drive voltage, electron current, ion current, or external modifying force (like microwaves) would cause variations in the time dependant distributions of electrons and ions (at least I assume so, especially if the plasma is not net neutral and or thermalized), with resultant changes in the Wiffleball volume, etc. This would make changes in the magnetic fields in the border reigons though electromagnetic interactions. In short there are multiple electronic and magnetic knobs that can be adjusted to achieve a percieved benifit. Inducing some resonate (?) mechanical vibration may even be usefull, provided it doesn't shake the machine apart.

Dan Tibbets

MSimon · Post by **MSimon** » Tue Oct 20, 2009 10:41 pm

D Tibbets wrote:
Aero wrote:
while the coil currents are being tweaked for spherical or spheroidal magnetic field oscillation.
I have an observation not specific to this thread, because several posts in several different threads have included comments similar to the above quote. I was (and still am) under the impression that superconducting magnets do not permit rapid fluctuation of the coil current. Are we expecting that we will be using copper coils, or am I wrong and the current in superconducting coils can be oscillated at reasonably high frequency?
When I make blanket statements about varing the electromagnetic fields, ion/ electron densitiy variations in volume and time space (?), I'm assuming knobs exist, despite my ignorance. I suspect your view on supermagnets are acurate. Copper coils could make up the main magnets, or be a suplimental magnet to quicky vary the overall magnetic field. Also any variation in the electron drive voltage, electron current, ion current, or external modifying force (like microwaves) would cause variations in the time dependant distributions of electrons and ions (at least I assume so, especially if the plasma is not net neutral and or thermalized), with resultant changes in the Wiffleball volume, etc. This would make changes in the magnetic fields in the border reigons though electromagnetic interactions. In short there are multiple electronic and magnetic knobs that can be adjusted to achieve a percieved benifit. Inducing some resonate (?) mechanical vibration may even be usefull, provided it doesn't shake the machine apart.

Dan Tibbets

Vibrating electric fields are easier and can be high (multi-MHz) frequency.

DeltaV · Post by **DeltaV** » Wed Oct 21, 2009 5:54 am

That makes sense. I hadn't considered before that capacitive reactance varies as 1/f and inductive reactance varies as f. If I recall correctly, the MLT performance should improve with higher f. So, it would then make more sense to implement the radially/rotationally symmetric (spherical/spheroidal) wiffleball variations (the higher frequency part) by changing the collective/individual coil-casing potentials, and the asymmetric wiffleball variations (the lower frequency part, which would determine thrust direction) by changing individual coil currents. Does this seem right?

MSimon · Post by **MSimon** » Wed Oct 21, 2009 6:15 am

DeltaV wrote:That makes sense. I hadn't considered before that capacitive reactance varies as 1/f and inductive reactance varies as f. If I recall correctly, the MLT performance should improve with higher f. So, it would then make more sense to implement the radially/rotationally symmetric (spherical/spheroidal) wiffleball variations (the higher frequency part) by changing the collective/individual coil-casing potentials, and the asymmetric wiffleball variations (the lower frequency part, which would determine thrust direction) by changing individual coil currents. Does this seem right?

It is difficult to say what should be done until there is a working machine. But that is how I would approach it.

DeltaV · Post by **DeltaV** » Fri Oct 23, 2009 2:46 am

Or, better yet, just leave the coil currents constant and do it all by way of the separated coil-casing potentials. Symmetrical POPS + asymmetrical thrust vectoring and (if any benefit is obtained) spheroidalization. If smooth thrust vectoring around the sphere is not practical due to the coarseness of a truncated-cube or dodecahedral magrid, maybe treat it like the discretized divert thrusters on a BMD kinetic kill vehicle. Each "divert thruster" being reusable for Polywell. I think the KKV versions are one-shots.