Wednesday, June 25, 2008


Critics are a very valuable resource if the criticism is based on reason. All designs should be thoroughly reviewed by their harshest reasonable critic. You get better designs that way. Or you kill bad investments before they get too big.

I have to say that right now just from an engineering perspective (assuming the physics works) the challenges of building a 100 MWth BFR are daunting. Not all of them have answers at this time.

Tuesday, June 24, 2008

Students Achieve Fusion

Students at Penninsula College have achieved fusion. I am more than a little proud to say I had a little to do with it. At least in so far as getting them on the right track.

Penninsula College Fusioneers

From left to right: Devon, Ivan, Sarah, Chris, Aaron, and Derek.

The Reactor

The Reactor

Peninsula College Glows

It glows

Which just goes to show that fusion research need not take big labs and big budgets. There is a lot that can be done in small labs to advance the state of the art. So let me encourage the rest of you: Start A Fusion Program In Your Own Home Town. America needs your help. The world needs your help.

Let me add that the genesis of this report was a bit done by ClassicPenny at Talk Polywell

Friday, June 20, 2008

You Have To Be A Little Crazy

Innovate Like Edison is a book about how to use Edison's system of innovation to improve business practices. Control Engineering discusses the book based on a talk given at the recent Society for Manufacturing Engineers Convention in Detroit, MI.
Detroit, MI – Understanding Thomas Edison’s patterns of thinking can help us be more like the guy who has 1,093 U.S. patents to his name, says co-author of the book, “Innovate Like Edison: The Success System of America’s Greatest Inventor.” Sarah Miller Caldicott, also Edison’s great grandniece, helped a packed room of engineers at the SME Annual Meeting gain insights into Edison’s thought patterns, to improve U.S. competitiveness.

Bearing a family resemblance to her great great Aunt Mina Miller – who married Edison in 1886 – and telling stories of growing up with Edison phonographs in her bedroom, Caldicott offered exercises which seemed to win over SME attendees... along with a promise of an autographed book.

Caldicott, also founder of The Power Patterns of Innovation, noted five best practices based on her 3-year study of Edison: a solution-centered mindset; kaleidoscopic thinking; full-spectrum engagement; master-mind collaboration; and super value creation.
All the points are covered in the review, but I'd like to take up this one:
-Cultivate a solution-centered mindset. Do not seize an answer at the beginning of an initiative. A framework of options and pathways can lead to solutions. Look outward and scan the environment. Lean ahead and hunt for a solution. Combine factual information with what-if or if-then thinking. Envision the solution and “emotionalize” the state that will be experienced upon getting there.
Which could be translated into be patiently crazy. Also note that emotion is considered an important part of rational thinking. In fact emotion may be one of the most critical feedback mechanisms. We have a very good pattern recognition system in our brains. If you train your brain with good patterns, after a while you get a "feel" about the right way and the wrong way to do things. Caldicott also goes into the need for thinking before acting. She even calls it contemplation. Be quiet. Sit Still. Shut up. And good preparation for that contemplation time is to get on the www and start looking around. Go deep. Some times the good stuff is on the 30th page of a search.

I always had a standard which I tried to stick to when it came to development: Five days of planning, two days of work. That is both imperative and descriptive. You must recognize that this method is scary for most management. The typical exhortation is: put in all the time you need to, but meet the schedule. My answer was: I'm not putting in any extra time. I will meet your schedule. In two days I will have a plan. How did that work out? Three months were alloted to get the project on track. I did it in five weeks. Without raising a sweat. Of course once you have proven yourself it is easier the next time.

Saturday, June 14, 2008

Some Objections - Some Answers

Art Carlson, who was commenting on an Alan Boyle article about the progress the EMC2 team was making with the Bussard Fusion Reactor tests, had some objections to the whole concept.
It's fun to daydream, isn't it? And it's easy, too, as long as you don't know too much.

There's more reasons than you can shake a stick at that this won't work. For starters, you can forget about aneutronic fusion. It's not just the temperature, Bremstrahlung is almost to certain radiate more energy than you produce by fusion no matter how good your confinement is. Even if you somehow manage to get a decent power balance, for a given plasma pressure and fusion power, a p-B11 reactor would have to be about 1000 times bigger (and more expensive) than a corresponding D-T reactor.

The next thing to worry about is the electrons. The magnetic configuration has not only lines of radial field from the center to the edge, which is bad enough judging from the experience with mirror machines, it also has lines of *zero* field along which the electrons will gush out. The idea of recycling electrons lost through the cusps won't work because they will come out almost parallel to the field but hit the return cusp with a large perpendicular velocity component they picked up going around the bend.

And the ions? The device is conceived to utilize a bi-modal velocity distribution, which will be destroyed very quickly by the two-stream instability. The anisotropy of the velocity distribution is also know to be a big problem, again from experience in the mirror program.

We haven't even started to talk about energy loss to the grids, the consequences of tiny field misalignments, charge-exchange ion losses, energy coupling between electrons and ions, and whether the potential distribution envisioned is even possible at a non-trivial ion density.

Since they managed to sweet talk somebody into giving them money, let them finish and publish their results, but let's not stop looking for ways to save energy and trying to develop other, less sexy but more reliable energy sources.

Art Carlson, Munich, Germany (Sent Friday, June 13, 2008 1:17 PM)
rnebel who is conducting the test and is definitely not day dreaming had a response.
Just a few comments for Mr. Carlson

1. The theory says that you can beat Bremstrahlung, but it's a challenge. The key is to keep the Boron concentration low compared the proton concentration so Z isn’t too bad. You pay for it in power density, but there is an optimum which works. You also gain because the electron energies are low in the high density regions.

2. The size arguments apply for machines where confinement is limited by cross-field diffusion like Tokamaks. They don't apply for electrostatic machines.

3. The Polywell doesn't have any lines of zero field. Take a look at the original papers on the configuration. See :
Bussard R.W., FusionTechnology, Vol. 19, 273, (1991) .
Krall N.A., Fusion Technology. Vol. 22, 42 (1992).

Furthermore, one expects adiabatic behavior along the field lines external to the device. Thus, what goes out comes back in. Phase space scattering is small because the density is small external to the device.

4. The machine does not use a bi-modal velocity distribution. We have looked at two-stream in detail, and it is not an issue for this machine. The most definitive treatise on the ions is : L. Chacon, G. H. Miley, D. C. Barnes, D. A. Knoll, Phys. Plasmas 7, 4547 (2000) which concluded partially relaxed ion distributions work just fine. Furthermore, the Polywell doesn’t even require ion convergence to work (unlike most other electrostatic devices). It helps, but it isn’t a requirement.

5. The system doesn’t have grids. It has magnetically insulated coil cases to provide the electrostatic acceleration. That’s what keeps the losses tolerable.

6. The electrostatic potential well is an issue. Maintaining it depends on the detailed particle balance. The “knobs” that affect it are the electron confinement time, the ion confinement time, and the electron injection current. There are methods of controlling all of these knobs.

rnebel (Sent Friday, June 13, 2008 6:17 PM)
One must be wary of a certain kind of dreamer:
All men dream, but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act their dream with open eyes, to make it possible.
—T. E. Lawrence from "Seven Pillars of Wisdom"

Friday, June 13, 2008

Fusion Report 13 June 008

Alan Boyle has a new report on the goings on in New Mexico at EMC2 Fusion Labs.
Emc2 Fusion's Richard Nebel can't say yet whether his team's garage-shop plasma experiment will lead to cheap, abundant fusion power. But he can say that after months of tweaking, the WB-7 device "runs like a top" - and he's hoping to get definitive answers about a technology that has tantalized grass-roots fusion fans for years.
Dr Nebel has been rather quiet lately in the usual forum he frequents, so this update is very welcome to all us grass-roots fusion fans.
"We're kind of a combination of high tech and Home Depot, because a lot of this stuff we make ourselves," Nebel told me today. "We're operating out of a glorified garage, but it's appropriate for what we're doing."

The Emc2 team has been ramping up its tests over the past few months, with the aim of using WB-7 to verify Bussard's WB-6 results. Today, Nebel said he's confident that the answers will be forthcoming, one way or the other.

"We're fully operational and we're getting data," Nebel said. "The machine runs like a top. You can just sit there and take data all afternoon."
Now compare "We're operating out of a glorified garage... with ITER's 30 % cost over run so far.
an independent panel of experts will be coming to Santa Fe this summer to review the WB-7 experiment, Nebel said.

"We're going to show them the whole thing, warts and all," he said.

Because of the complexity, it will take some interpretation to determine exactly how the experiment is turning out. "The answers are going to be kind of nuanced," Nebel said.

The experts' assessment will feed into the decision on whether to move forward with larger-scale tests. Nebel said he won't discuss the data publicly until his funders have made that decision.
"Warts and all now isn't that refreshing.
Nebel may be low-key about the experiment, but he has high hopes for Bussard's Polywell fusion concept. If it works the way Nebel hopes, the system could open the way for larger-scale, commercially viable fusion reactors and even new types of space propulsion systems.

"We're looking at power generation with this machine," Nebel said. "This machine is so inexpensive going into the 100-megawatt range that there's no compelling reason for not just doing it. We're trying to take bigger steps than you would with a conventional fusion machine."
With my typical engineering sensibilities I still think some intermediate steps would be required. Like a continuously operating experiment. It need not be a very big machine but it will require a big power supply. It might need to draw 4 to 6 MW on start up. In fact it might need that for the whole duration of operation. The machine scales in a funny way. Coil power (for a copper coil demo) goes up as the reactor gets large but the accelerator power goes down.
Over the next decade, billions of dollars are due to be spent on the most conventional approach to nuclear fusion, which is based on a magnetic confinement device known as a tokamak. The $13 billion ITER experimental plasma project is just starting to take shape in France, and there's already talk that bigger budgets and longer timetables will be required.

If the Polywell system's worth is proven, that could provide a cheaper, faster route to the same goal - and that's why there's a groundswell of grass-roots interest in Nebel's progress. What's more, a large-scale Polywell device could use cleaner fusion fuels - for example, lunar helium-3, or hydrogen and boron ions. Nebel eventually hopes to make use of the hydrogen-boron combination, known as pB11 fusion.

"The reason that advanced fuels are so hard for conventional fusion machines is that you have to go to high temperatures," Nebel explained. "High temperatures are difficult on a conventional fusion machine. ... If you look at electrostatics, high temperatures aren't hard. High temperatures are high voltage."

Most researchers would see conventional tokamak machines as the safer route to commercial fusion power. There's a chance that Bussard's Polywell dream will prove illusory, due to scientific or engineering bugaboos yet to be revealed. But even though Nebel can't yet talk about the data, he's proud that he and his colleagues at Emc2 have gotten so far so quickly.

"By God, we built a laboratory and an experiment in nine months," he said, "and we're getting data out of it."
By God I hope it works out.

If you want to know what you can do to help have a look at Starting A Fusion Program In Your Home Town.

H/T Instapundit

Sunday, June 8, 2008

Literate Programming

Literate Programming
Donald Knuth. "Literate Programming (1984)" in Literate Programming. CSLI, 1992, pg. 99.

I believe that the time is ripe for significantly better documentation of programs, and that we can best achieve this by considering programs to be works of literature. Hence, my title: "Literate Programming."

Let us change our traditional attitude to the construction of programs: Instead of imagining that our main task is to instruct a computer what to do, let us concentrate rather on explaining to human beings what we want a computer to do.

The practitioner of literate programming can be regarded as an essayist, whose main concern is with exposition and excellence of style. Such an author, with thesaurus in hand, chooses the names of variables carefully and explains what each variable means. He or she strives for a program that is comprehensible because its concepts have been introduced in an order that is best for human understanding, using a mixture of formal and informal methods that reinforce each other.
I have always programmed like that once I started writing professionally in Forth. Leo Brodie's book Thinking FORTH [free download] was all about using the literate style. The most important thing after Naming the Parts is good factoring.

Friday, June 6, 2008

CAN Bus And System Control

I like CAN (Controller Area Network) Bus for control systems. It has moderate speed (1 Mbs), it is deterministic., it has priority control for multi-master operation, and because of its use in autos it is robust and low cost. In addition it has been on the market for about 10 years so it is well established with lots of vendors to choose from. In addition there are a number of MCUs with built in CAN.

For test reactor operation I see a hierarchy of CAN buses, each devoted to a given function and then all melded into a master bus. Let me start with the sub nets.

1. Vacuum Gauge/Vacuum Pump Control Bus
2. HV Power Supply Internal Buses
3. Instrumentation Buses (Temp Monitoring, Flow Monitoring, Master Clock, Neutron Counter, Electrical Power Measurement and Control, etc.)
4. Auxiliary Control (Electrical Power Measurement and Control, etc.)

And then a master bus to send messages to/from the sub buses.

I haven't decided on an MCU yet. One of the requirements would be that it is FLASH programmable and have a built in CAN bus. I have been thinking about pressure measurement lately so I'd like to lay out what a CAN bus interface would look like.

The pressure transducers I have in mind (MKS 722 and MKS 626A) have a 0 to 10 V output. I haven't picked any other components yet. So we will just look at functions.

1. Pressure (dependent on transducer - from 1000 torr to .1 torr full scale, 17 bits)
2. Board temperature (0 to 100 deg C, nominal 30 deg C 10 bits nominal - 8 actual)
3. Board power bus voltage (20 to 60V, nominal 48VDC, 10 bits nominal - 8 actual)
4. Board power bus current (0 to 255 mA, nominal TBD, 10 bits nominal - 8 actual)
5. Various internal power supplies (TBD, TBD, 10 bits nominal - 8 actual)
6. Isolated CAN supply, Isolated Pressure transducer supply, Isolated MCU supplies.

Lets start with the transducer front end. It should have an op-amp (fully differential).

For the 24 bit converter I like the AD7767 it has an accuracy of 17 bits which matches the one part in 1e5 resolution of the pressure transducer.

The ADA4941-1 is a nice companion amplifier. And the ADR425 looks like a nice reference. Good specs, not too expensive.

That covers the main parts of the analog side. What about the computing side? I have been looking around and I think I like the Fujitsu CAN bus microprocessors the best. Its architecture is a mixture of a FORTH engine and a Z8 register bank.

Fujitsu 16 bit microcontrollers

Fujitsu 32 bit microcontrollers

Fujitsu microcontrollers

I haven't addressed the CAN interface yet. It is pretty simple: a few high speed optocouplers, a bus driver chip, a separate isolated power supply, some protection components and away we go.

Let me add that Fujitsu has 8 bitters that I have yet to take a serious look at. I'll probably remedy that in the next few days.

The Atmel CAN processors would be a good second choice. The reason I like the Fujitsu stuff better is that it has a very good migration path and I'd like to use one software model for as many of the process tasks as possible.

I also like the Infineon TC1166 32 bit processor with CAN. Digikey sells them for about $39 ea. Quantity one. Since programming and hardware design is going to be the big cost for the initial units I'm going to do what Chuck Moore suggests. Get the biggest fastest processor you can afford to start. Then reduce the foot print if volumes warrant.

The Fujitsu part is more open ended and has a very simple CALL structure. However, there are no automatic register saves with calls. Thus every CALL must have at least one PUSH and one POP if you expect nested calls. The Infineon has a more definite programming model with user space registers and system space registers. They each save registers on a CALL (but different sets). The cost is 2 to 5 clocks. Not a big hit (but they could have done better). The Infineon part also seems like it might be harder to learn due to instruction pipeline flushing requirements in some situations that require an instruction to finish before the following instruction(s) are executed. I do like the floating point and some other features of the Infineon, but I will set it aside for now. Well I read on and find that the Fujitsu Part also has a 5 deep pipeline. I guess when you need to flush it you just do a bunch of no-ops.

The Fujitsu also is more deterministic and can do tail end recursion since the pipeline is only one level deep (actually it is five deep also but it can do tail end recursion.). However the divide routines are not as mechanized as they are in the Infineon. Since I hardly ever use them except with user input to precalculate multiply constants that is not such a big hit.

Update 09 Jun 1534z

I have been looking at the Freescale MPC551x MPUs. I like them. Plus Freescale gives away an assembler good enough to get a FORTH up on the chip.

I like the Atmel ATA6660 CAN bus physical interface. There are later and greater chips out with more functionality , however I like to keep the interface simple and electrically isolated. You can do that with three high speed optocouplers and an isolation supply. A 48 V to 5 V job at about 1 W would be good.


The FORTH programming system is one of my favorites. The language is simple, compact, and extremely powerful, and almost dead. It has been kept alive over the years by a few fanatics including myself. Well, it looks like it is coming back in a big way. A lot of big names are now into the game.
By INQUIRER staff: Friday, 07 December 2007, 2:40 PM

PATRIOT SCIENTIFIC, which jointly owns a microprocessor related patent porfolio, said that Taiwanese firm Lite-On has bought a licence, becoming the third firm in a week to do so.

According to the firm, it's the first Taiwanese system company to buy a licence. Daewoo and a US manufacturer said they'd buy a licence earlier this week.

The firm's "Moore Microprocessor Patent Portfolio" that holds IP including seven US patents covering microprocessors, system on chip stuff, and microcontrollers.

This lot have also signed up for licences already. AMD, Intel, Hewlett Packard, Casio, Fujitsu, Sony, Nikon, Seiko Epson, Pentax, Olympus, Kenwood, Agilent, Lexmark, Schneider Electric, NEC Corporation, Funai Electric, Sandisk, Sharp Corporation, Nokia, Bull, Lego, DMP Electronics, Denso Wave, Philips, TEAC, Daewoo Electronics. And now Lite-On.
Now that looks like a rush. Why? Well, a dual stack architecture is pretty well fitted to C. Although C is no near as efficient as FORTH with such an architecture. EE Times Asia has more on the story.
06 Mar 2006

Alliacense announced that Fujitsu Ltd has licensed its intellectual property protected by the Moore Microprocessor Patent (MMP) portfolio. Alliacense is the subsidiary created last year to administer the portfolio on behalf of owners Patriot Scientific Corp. and TPL Group Financial terms of the licensing arrangement were not disclosed.

Fujitsu becomes the third system manufacturer to publicly disclose licensing of the MMP portfolio, following Hewlett-Packard (HP) in January and Casio Computer Co. Ltd last week. In announcing the Casio deal last week, Patriot Scientific revealed that semiconductor makers like Intel Corp. and Advanced Micro Devices (AMD) are not being required to pay royalties on MMP licenses.
Note the earlier date. About a year and a half before the Dec 007 announcement. Also note that I have a friend who works for the TPL Group. I'll have to ask him what happened.

In any case a little more background from the March 006 article:
Patriot and TPL came together in June 2005 to settle a long-standing patent dispute so they could jointly pursue licensing revenue from third parties. The TPL Group has been granted full responsibility and authority for the commercialization and licensing of a unified portfolio of 10 patents.

The MMP portfolio is named after inventor Charles H. Moore, chief technology officer of TPL Group, who is known for inventing the Forth software programming language and for his work in the 1980s on stack-based microprocessors.
It looks like FORTH as a chip architecture is back big time. I wonder if the language will come back as well.

In any case I really like the Fujitsu 16 bit and the Fujitsu 32 bit versions of the architecture.

The Infineon TC1166 32 bit processor looks nice. Digikey sells them for about $39 ea. Quantity one. Since programming and hardware design is going to be the big cost for the initial units I'm going to do what Chuck Moore suggests. Get the biggest fastest processor you can afford to start. Then reduce the foot print if volumes warrant.

Wednesday, June 4, 2008

Gauging With Intent

We are going to have to read pressures both for experimental purposes and to decide when to turn pumps off and on. Of course first start with minimalist education available on page 7 of this [pdf]. The first critical piece of data is that only capacitance gauges are gas independent. The second critical bit is that the output is linear with pressure and they can cover a 10,000 to 1 pressure range. i.e. 1 millivolt to 10 Volt output.

The Adixen Capacitance Vacuum Gauges come in four models.

1100 to 1e-1 torr
110 to 1e-2 torr
11 to 1e-3 torr
1.1 to 1e-4 torr

Two is probably the minimum for a system. One (1100 torr to 1e-1 torr) to monitor the backing pump inlet pressure. Plus one other chosen for the chamber operating pressure. The 110 to 1e-1 torr model would be good for most current fusor experiments. The minimum output to realize the inherent accuracy of the instruments is around 20 to 50 mV.

Here are some more capacitance gauges.

MKS 722 which has some really nice specs but only comes in a KF 16 flange. Which means an adapter. It covers the 1 torr to 1000 torr full scale range. Around $900 with flange mount. Add about $100 for a flange adapter.

MKS 626A can be ordered with a CF40 (2 3/4") flange. Full scale ranges from .1 torr to 1,000 torr. Around $950 with flange mount.

What if you want to go to lower pressures? I'll go into that in another post.

Monday, June 2, 2008

Fusor Vacuum Pump Choice

I have been neglecting general education on vacuum pumps. So here is Technical Notes on Various Vacuum Pump Types. And of course the wiki on Vacuum Pumps. All for the purpose:

I'm trying to decide on a vacuum pump set up and have come up with two candidates based on their compression ratios for H2:

Adixen ATH31+. 1E11 N2, 1E5 H2 Compression Ratio
Aprox Prices:about $4,700 pump, about $1,700 controller, about $600 required accessories. 4 1/2" CF High Vacuum connection.

Pfeiffer TMU 071YP >1E11 N2, 1E5 H2 Compression Ratio
Aprox Pricesabout $5,200 pump, about $1,300 controller. 4 1/2" CF High Vacuum connection.

l/s CR TU Wt IF OF FP FPS $Pmp $Cnt
ATH 31+141e55e-102.74.5" CFKF16451$4,700$1700
TMH071P421e55e-108.44.5" CFKF16182.5$5,208$1,298

l/s = Pump Speed in liters per second For H2
CR = Compression Ratio H2
TU = Ultimate pressure in mbar
Wt = weight lbs
IF = Input (High Vacuum) Flange
OF = Output (Fore Pump) Flange
FP = Max Foreline Pressure mbar
FPS = Min Foreline Pump Speed m^3/hr
$Pmp = Cost of the Pump
$Cnt = Cost of the Controller

The Pfeiffer looks like a better pump for the money. A lot will depend on the fore pump. I'm leaning to a roots blower or some other oil less type pump. So let us look at some. First some education: Scroll vs Rotary Lobe Pumps.

IDP-3, technical [pdf], dry scroll, 3 m3/hr rate, 2.5e-1 torr. ultimate, $2,650

ACP15, technical [pdf], rotary lobe, 14 m3/hr rate, 3.8e-2 torr. ultimate, $5,134

1 torr = 1.33 mbar

Sunday, June 1, 2008

Vacuum Flanges

DNNWTube ID. mmCF Flange O.D.
CF Flange O.D. (inches)
DN161616341 1/3"
DN252522-54(2 1/8")
DN403535702 3/4"
DN505047-86(3 3/8")
DN6363571144 1/2"

Taken from 5Pascal [pdf]