Thursday, June 18, 2009

Room Temperature Superconductors One Step Closer

We are one step closer to room temperature superconductors.
Menlo Park, Calif.—Move over, silicon—it may be time to give the Valley a new name. Physicists at the Department of Energy's (DOE) SLAC National Accelerator Laboratory and Stanford University have confirmed the existence of a type of material that could one day provide dramatically faster, more efficient computer chips.

Recently-predicted and much-sought, the material allows electrons on its surface to travel with no loss of energy at room temperatures and can be fabricated using existing semiconductor technologies. Such material could provide a leap in microchip speeds, and even become the bedrock of an entirely new kind of computing industry based on spintronics, the next evolution of electronics.

Physicists Yulin Chen, Zhi-Xun Shen and their colleagues tested the behavior of electrons in the compound bismuth telluride. The results, published online June 11 in Science Express, show a clear signature of what is called a topological insulator, a material that enables the free flow of electrons across its surface with no loss of energy.
Pretty darn exciting. It all depends on something called topological insulation. The article gives some details on how that works. Which gets a bit heavy on the physics. I'm going to skip that here. However, if you have heard of the Pauli exclusion principle it is worth a read.

There are some limitations. For now.
Topological insulators aren't conventional superconductors nor fodder for super-efficient power lines, as they can only carry small currents, but they could pave the way for a paradigm shift in microchip development. "This could lead to new applications of spintronics, or using the electron spin to carry information," Qi said. "Whether or not it can build better wires, I'm optimistic it can lead to new devices, transistors, and spintronics devices."

Fortunately for real-world applications, bismuth telluride is fairly simple to grow and work with. Chen said, "It's a three-dimensional material, so it's easy to fabricate with the current mature semiconductor technology. It's also easy to dope—you can tune the properties relatively easily."

"This is already a very exciting thing," he said, adding that the material "could let us make a device with new operating principles."
Bismuth Telluride is a semiconductor that is currently used for solid state refrigerators. It is also used to generate electricity from small temperature differences. That means the semiconductor industry has more than a little experience in fabricating the material.

If the lab boys have developed a repeatable formula it is possible we might see useful devices using this superconducting property in as little as three years. One use of such properties might be to make a super low noise microwave filter that doesn't require cooling to Liquid Nitrogen temperatures (77° Kelvin). That could be very helpful.

I will be keeping an eye on this one.

If "normal" superconductivity interests you this book is a good place to start:
Introduction to Superconductivity

And if you are a little further along and contemplate building a fusion reactor in your garage, this book could help:
Case Studies in Superconducting Magnets: Design and Operational Issues

More books:


Handbook of Superconductivity

Engineering Superconductivity

Wednesday, June 17, 2009

The Boys At Talk-Polywell Have Struck Paydirt

The boys at Talk Polywell have uncovered the details of the WB-8 contract [pdf]. Those details can give us some insight into how WB-7 has gone. From the looks of things - rather well.
The current effort will build on what has been completed under these previous contracts as well as requirements to provide the Navy with data for potential applications of AGEE with a delivered item, wiffleball 8 (WB8) and options for a modified wiffleball 8 (WB8.1) and modified ion gun. The objective of this procurement is validation of the basic physics of the AGEE concept as well as requirements to provide the Navy with data for potential applications of AGEE. It builds upon previous concept-demonstration bench top versions of plasma wiffleballs. As such, it comes under the FAR 35.001 definition of applied research. The contract will be for a wiffleball 8 with 2 options for modifications to the wiffleball based upon it’s success.
OK. They are going into deeper validation. Which means WB-7 went OK.
3.1.1 The Contractor shall construct and test a small-scale MG Insulated, Wiffleball Polyhedral Device, WB8. WB8 shall be built based on results of WB7 (built under contract N68936-03-C-0031) and shall utilize design and performance knowledge gained from test of prior WB machines.

3.1.2 The design shall use circular coils around each main face cusp axis. The device shall use emitter electron gun arrays and an ion beam drive. The machine will be operated in magnetic fields with pulsed currents. WB8 shall be operated at a magnetic field strength of approximately 0.8 Tesla, which represents an increase of 8 times the magnetic field strength of previous WB machines. Improvements over previous WB machines in WB confinement, ion energy and fusion reactivity are expected as a result of these changes to WB machine design.

3.1.3 Within 20 days of completion of testing of the WB8, the contractor shall deliver a report detailing the results of the experimental testing of this MG Insulated, Wiffleball Polyhedral Device, WB8. The report shall provide sufficient information to guide programmatic and design decisions about further, refined design efforts for similar devices. The report shall address the plasma dynamics of WB devices, and shall address the scaling laws that apply to polywell fusion. (A001)
Circular coils means that there will be no significant change in geometry. That is good. Apples to apples comparisons. An increase of field strength by a factor of 8 means - if the scaling laws hold a factor of about 4,000 increase in power out. If WB-7 was similar to WB-6 it means an increase from 3 neutrons a shot to 12,000. A real countable number i.e the error bars will be much lower. A count of 3 can actually be considered a count of 3 +/-2. That is a big error bar. For 12,000 the error bar is on the order of +/-100 about 1%. That makes improvements or degradations of 5% easily detectable. Where as in the first situation (WB-6/7) changes that doubled or halved the output rate would be hard to detect.
3.1.4 Within 30 days of build and test of WB8, the contractor shall provide a predictive model of WB behavior including data points for detailed 2D/3D profile measurements of plasma density, ion energy and WB magnetic field structure during follow-on tests to validate the scientific basis for a Polywell fusion power reactor, and guide further research. The contractor shall coordinate with the Government for a program review meeting at the contractor’s facilities to be held no later than 40 days after the testing of the WB8 and shall provide the detailed predictive model and data points at this program review meeting.

3.1.5 The contractor shall deliver a periodic progress report specifying status information of the experimental testing of the MG Insulated, Wiffleball Polyhedral Device, WB8. (A002)
The magnetic profile of an operating device is critical for knowing how the device actually operates. Without that it is very difficult if not impossible to design in improvements.
3.1.6 The contractor shall deliver a conceptual design for a follow-on fusion demonstration device, WB-9. Conceptual studies will focus on the feasibility of extending the WB-8 results to this device and determining the suitability of this concept as a fusion reactor. This design will be delivered at the end of the contract.
So the program is starting to take on a life of its own. A WB-9 device is already under consideration even before experiments on WB-8 are even completed. This indicates a fair amount of confidence in the forthcoming results. Excellent.

Now here comes what I consider the most critical requirement of WB-8testing.
3.2.1 Enhanced Ion Drive with PB11 (proton/boron 11): Based on the results of WB8 testing, and the availability of government funds the contractor shall develop a WB machine (WB8.1) which incorporates the knowledge and improvements gained in WB8. It is expected that higher ion drive capabilities will be added, and that a “PB11” reaction will be demonstrated. The contractor shall investigate and validate the plasma scaling laws with respect to B-field, voltage and reactor size. The contractor shall investigate the feasibility of a neutron-free fusion power reaction using a polywell WB machine. It is anticipated that improvements in WB confinement, ion energy, and fusion reactivity will be demonstrated in WB8.1. Improvements over the WB8 predictive, computational model are expected, which should yield a better understanding of the WB fusion reaction thus allowing optimization of the WB machine.

3.2.2 The contractor shall deliver a report detailing the results of the experimental testing of WB8.1. The report shall provide sufficient information to guide programmatic and design decisions about further, refined design efforts for similar devices. The report shall address the plasma dynamics of WB devices, and shall address the scaling laws that apply to polywell fusion, and the feasibility of the PB11 reaction. The report shall address the conceptual requirements for a polywell fusion reactor capable of generating approximately 100mW. (A0001)

3.2.3 Within 30 days of testing, the contractor shall update the predictive computer model of WB behavior created under paragraph 3.1.4 using the PB11 reaction and shall deliver the model within 30 days of completion of initial tests specified in paragraph 3.2.1.
The fact that they are contemplating work on the pB11 reaction is very encouraging. That fuel is one of the most difficult to burn in a fusion reactor. Which means testing with lesser fuels (or simulated fuels) has gone very well indeed.

At 100 milliwatts for a follow on reactor they are starting to get into the power range. If they can get that kind of power with .3 m dia. coils and .8 T fields, then a reactor with 3 m coils and 10 T fields should produce about 2.5 Mega Watts if the scaling laws hold.

And just as a little kicker:
3.3.1 The contractor shall develop an enhanced ion drive system that is compatible with Wiffleball 8.1 and projected future wiffleballs. The ion drive system shall be capable of injecting protons (ionized Hydrogen), and ionized Boron 11. The ion drive system shall be capable of generating ions in sufficient quantity to fully fuel the wiffleball fusion machines.
If they are going to fuel even a small machine the ion guns are going to have to be capable of multi amp currents - each.

Well that is my first cut at digesting the news. If you want to figure out more a look at all the links at Talk Polywell will be helpful. I especially liked this inventory [pdf] of items purchased since about 1999.

All in all the new contract has a lot of good news. To sum up:

What it means about past work: it went well.
What it means for the future: verifying engineering rules
More: there is a plan to test the Hydrogen/Boron 11 fuel combination
More: They must be confident of results since they are planning a WB-9

You can learn the basics of fusion energy by reading Principles of Fusion Energy: An Introduction to Fusion Energy for Students of Science and Engineering

Polywell is a little more complicated. You can learn more about Polywell and its potential at: Bussard's IEC Fusion Technology (Polywell Fusion) Explained

The American Thinker has a good article up with the basics.

Why hasn't Polywell Fusion been fully funded by the Obama administration?

Tuesday, June 2, 2009

The Feynman Physics Lectures

The Feynman Lectures on Physics

Let me put it to you straight and simple. If you do not own this set of books and peruse it as bedtime reading three times a week or more you will not be able to fully participate in the Polywell Project except as an interested observer. Of course if you have the time put in an hour or two a day of serious study.

Don't get me wrong. This project needs tens of millions of interested observers. I welcome every one. Bring your friends and relatives, children, cats, and dogs. Parrots too. Especially parrots named Poly.

But if you are going to do physics or engineering these books are treasures. Not just for the understanding behind them but also for the feel Feynman has for the subject.