TheRadicalModerate wrote:Dan--
Here's the main patent. There are others mentioned up-thread, but I haven't gone through those.
The patent
never mentions a potential well, although it does refer to a magnetic well. (I just did a search through the text.)
The patent application mentions lots and lots of embodiments... how do you patent that?
In the patent the only heating mechanism mentioned is neutral beam.
They do mention varying the plasma shape asI have pointed out in the past.
"For example, the central confinement well can be expanded into a more spherical shape, increasing its volume and suitability for non-thermal fusion schemes. Another example is the stretching of the central region into a more elongated cigar shape, perhaps for easier integration into aerospace vehicles or for easier power conversion or surface wall effects such as breeding. "
"The addition of two axial ‘mirror’ coils (i.e., mirror coils 160) serves to decrease the axial cusp losses and more importantly makes the recirculating field lines satisfy average minimum-p, a condition not satisfied by other existing recirculating schemes. In some embodiments, additional pairs of internal coils "
The external magnets do compress the field lines as they loop around between cusps. This may help in recirculating electrons and fuel ions. But it may have more importance for recirculating fusion ions- primarily alphas. They mention in the video that it is a D-T fueled ignition machine. As per Dr Nebel, this implies that the alphas mush hang around long enough to thermalize with the fuel ions. As per Dr Nebels, the alphas in the Polywell last only about a few thousand passes- a few thousand meters of travel distance, before they escape through a cusp. In the Polywell, they would be expected to hit a wall and not be recirculated. The B field loop is to large- the radius of the B field line would hit a wall before the alpha could loop around. With external magnets, perhaps the mildly lower energy alphas from D-T fusion may be recirculated through neighboring cusps multiple times to provide the necessary dwell time for thermalization with the fuel ions. Defiantly no direct conversion, only heat transfer for powering electricity generation.
The issue of ion ExB diffusion is not answered. They do mention something about ion gyroradius multiples needing to be met. Somewhere in the 5-7 range? This is actually comparable to the electron gyro radius clearance needed in the Polywell. But, being ions, the clearance would have to be greater by a factor of ~ 60 or more- either increased B field strength, or greater machine size. This is a major consideration that Bussard pointed out . How they can claim a small high density machine like the Polywell without the fuel ions being decoupled from Magnetic ExB loss mechanism s a mystery. That they apparently only propose D-T fusion, a target plasma temperature of perhaps 20 KeV versus 100 Kev for D-D fuel mitigates the ExB jump distance issue somewhat.
The original video which started all of this-
http://aviationweek.com/technology/skun ... or-details
"The CFR is expected to have a beta limit ratio of one. “We should be able to go to 100% or beyond,” he adds."
"This crucial difference means that for the same size, the CFR generates more power than a tokamak by a factor of 10. This in turn means, for the same power output, the CFR can be 10 times smaller. The change in scale is a game-changer in terms of producibility and cost, explains McGuire. “It’s one of the reasons we think it is feasible for development and future economics,” he says. “Ten times smaller is the key."
“We also have a recirculation that is very similar to a Polywell concept,” he adds, referring to another promising avenue of fusion power research. A Polywell fusion reactor uses electromagnets to generate a magnetic field that traps electrons, creating a negative voltage, which then attracts positive ions. The resulting acceleration of the ions toward the negative center results in a collision and fusion. "
The prototype would demonstrate ignition conditions and the ability to run for upward of 10 sec. in a steady state after the injectors, which will be used to ignite the plasma, are turned off. “So it wouldn’t be at full power, like a working concept reactor, but basically just showing that all the physics works,” McGuire says.
https://www.youtube.com/watch?v=JAsRFVbcyUY
The video mentions plasma heating via microwaves. Admittedly, I though it had mentioned a potential well, but no... Mention of D-T reaction, lithium breeding, etc. And, is this supposed to fit on a truck or in a plane? Lots of luck on that.
So, my current appreciation for the Lockheed design is that it is like a Polywell in that it confines plasma in a cusp magnetic field and can have a central point- 'quasi spherical'. Recirculation of fuel plasma, not just electrons is probable. recirculation may be more efficient (has to be) and also applies to escaping fusion alphas- in order to reach ignition conditions. This removes the opportunity for direct conversion.
Heating is by conventional neutral beam/ microwave heating. No mention of a potential well, and thus no decoupling of fuel ion containment from magnetic containment, no central confluence possible, and no monoenergetic conditions possible. MHD stability/ edge stability issues are probably not significant for reasons I postulated in my previous post.
No possibility of advanced fuel usage except small chance of D-D.
ExB ion issues seem paramount. If Bussards, Nebels, , etc. understandings are pertinent, I am leery of Lockheeds expectations.
This current Lockheed design, based on the limited information released, and my understanding seems tentative at best.
They have stressed though that they are concentrating on magnetic confinement issues. If they introduce a electrostatic potential well as part of the design at a latter stage, the idealized advantages of the Polywell could be met, at least for a thermal machine driving a gas turbine. Direct conversion possibilities would seem to be excluded. And, I am uncertain of Bremsstruhlung consequences.
Dan Tibbets