January 10, 2008

Bussard's inertial electrostatic confinement fusion WB-7 prototype activated

EMC2 Fusion has built an upgraded model of Bussard's last experimental plasma containment device, which was known as WB-6. "We got first plasma yesterday," Nebel said - but he and his colleagues in Santa Fe, N.M., still have a long way to get the WB-7 experiment up to the power levels Bussard was working with.


Older prototype

This work is very important because we could have commercial fusion in as little as 5 years if the work is successful. Success would also transform space travel. (40 to 1000 times cheaper to get into space)

WB-6 (the previous prototype) had 2.5 billion fusions per second

The initial analysis showed that Bussard's data on energy yields were consistent with expectations, Nebel said.

He said he's hoping to find out by this spring whether or not Bussard's concept is worth pursuing with a larger demonstration project.

"We don't know for sure whether all that's right," he said, "but it'd be horrible for Mother Nature to give you what you expect to see, and have it all be bogus."


Introduction to IEC fusion

This is paraphrasing from the Tom Ligon description.

IEC fusion uses magnets to contain an electron cloud in the center. It is a variation on the electron gun and vacuum tube in television technology. Then they inject the fuel (deuterium or lithium, boron) as positive ions. The positive ions get attracted to the high negative charge at a speed sufficient for fusion. Speed and electron volt charge can be converted over to temperature. The electrons hitting the TV screen can be converted from electron volts to 200 million degrees.

The old problem was that if you had a physical grid in the center then you could not get higher than 98% efficiency because ions would collide with the grid.

UPDATE: The problem with grids is that the very best you can do is 2% electron losses (the 98% limit). With those kinds of losses net power is impossible. Losses have to get below 1 part in 100,000 or less to get net power. (99.999% efficiency) [thanks to M Simon for the clarification]

Bussard system uses magnets on the outside to contain the electrons and have the electrons go around and around 100,000 times before being lost outside the magnetic field.

The fuel either comes in as ions from an ion gun or it comes in without a charge and some of it is ionized by collisions with the madly spinning electrons. The fuel is affected by the same forces as the electrons but a little differently because it is going much slower. About 64 times slower in the case of Deuterium fuel (a hydrogen with one neutron). Now these positively charged Deuterium ions are attracted to the virtual electrode (the electron cloud) in the center of the machine. So they come rushing in. If they come rushing in fast enough and hit each other just about dead on they join together and make a He3 nucleus (two protons and a neutron) and give off a high energy neutron.

Ions that miss will go rushing through the center and then head for one of the grids. When the voltage field they traveled through equals the energy they had at the center of the machine the ions have given up their energy to the grids (which repel the ions), they then go heading back to the center of the machine where they have another chance at hitting another ion at high enough speed and close enough to
cause a fusion.

Details of the polywell fusion reactor. (Polywell fusion and Inertial Electrostatic Confinement fusion are the same thing).

Easy low cost and very low radiation fusion

Previous bussard fusion update

UPDATE: A prediction on how this might play out if it is successful.

Oil prices can fluctuate for a lot of reasons. There is currently a $20-30 premium because of fear of more middle east conflict. The peak oil fears might also be adding $5-10 to the price per barrel. So any immediate hit to prices would be from changing the psychology around oil prices not from actual shifts in the economics of supply and demand. The supply and demand would get impacted over one to two decades. Once the full scale system is proved out then there would be a rush to build them.

I think if the prototypes pan out this spring, most people will not believe it. So I do not think the working prototypes should effect price more than $1-2 per barrel if anything. The working full scale system (in 3-8 years) $5-15 from a psychological shift. Maybe $20 with the optimism.

Just as the thermoelectrics have actual released products (car seat warmers) but most people do not believe that the better thermoelectrics in the labs are on the way starting within 5 years. However, it will take time for the thermoelectrics to be deployed.

The promise of highly successful first two prototypes WB7 and then WB8 should definitely green light the full scale positive power system. That would still take 5 years (maybe 2-3 if people got excited and accelerated development and effort with promising results and might take 8 years or more if there are unforeseen problems.)

From the descriptions it is clear that the IEC fusion devices are far simpler than the ITER tokomak fusion devices. It is also simpler than nuclear fission reactors. So success would mean faster transformation, but it would still take five to ten years for big infrastructure impact to the point that oil would start to be significantly displaced. Plus it would first hit coal for electricity. Unlike current fission reactors which take 4-6 years to build, these IEC fusion reactors might be buildable in 1-3 years. There is still the issue of licensing and regulatory approvals. It is not clear what that licensing/regulatory process would be but it should be shorter than nuclear fission licensing as the IEC fusion is easier to shutoff and does not have nuclear fuel or waste.

The full scale IEC fusion reactors would be about 4 meters in radius and weigh about 14 tons and generate 1GW and 8 meters for about 128GW. Power will be 5-20 times cheaper.

The power generator is about 10 to 12 ft across for an output between 100 MW and 1,000 MW. Power output scales as the 7th power of size. Double the size and you get 128X as much power.


FURTHER READING
Other coverage at power and control

And at Dean Esmay's site

Bussard had made a case that bremsstrahlung losses would not be an insurmountable problem to generating net power The successful operation of the WB7 prototype should prove whether Bussard was right or not.

Controversies exist over whether the ions and electrons will thermalise and whether bremsstrahlung losses will emit more energy in an unrecoverable form than can be produced by the fusion reaction.

According to Todd Rider in A general critique of inertial-electrostatic confinement fusion systems, net energy production is not viable in IEC fusion for fuels other than D-T, D-D, and D-He3, and breakeven operation with any fuel except D-T is unlikely. The primary problem that he discusses is the thermalization of ions, allowing them to escape over the top of the electrostatic well more rapidly than they fuse. He considers his paper optimistic because he assumes that core degradation can be countered.

Nevins makes an argument similar to Rider's in [W.M. Nevins, Phys. Plasmas <2> (10), 3804 (October, 1995)], where he shows that the fusion gain (ratio of fusion power produced to the power required to maintain the non-equilibrium ion distribution function) is limited to 0.1 assuming that the device is fueled with a mixture of deuterium and tritium. A fusion gain of about 10 is required for net energy production.


From M. Simon's explanation in comments:
Rider's chief criticism is related to the recirculating power required in a colliding beam machine: "In virtually all cases, this minimum recirculating power is substantially larger than the fusion power, so barring the discovery of methods of recirculating the power at exceedingly high efficiencies, reactors employing plasmas not in thermodynamic equilibrium will not be able to produce net power". This is a very valid criticism and is acknowledged by Robert Bussard. However, Bussard claims that the discovery of what he terms the Wiffle Ball effect and by circulating electrons escaping from the Wiffle ball at high efficiencies he can get the total electron circulation efficiency into the 99.999% to 99.9999% range, making colling beam machines of his proposed design viable for power production. Experiments are currently under way (Jan. 2008) to test Dr. Bussard's ideas.

Форма для связи

Name

Email *

Message *