Mechanical Design: Open FEM

Open FEM is a mechanical design program that can help figure out the stresses and strains caused by the magnets in a Bussard Fusion Reactor. It is based on Scilab, a numerical computation program.

H/T Prometheus Fusion Perfection

Critics

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.

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.

Reactor Size

I was rereading Sekora's paper on POPS [pdf] and came across this gem.

It is very difficult to achieve field strength approximately 50-100 kV/cm without causing arcing.The maximum field strength is governed by the Paschen curve.

So let us look at what a decelerator BFR might look like. Reaction volume 1 meter radius. That is a given. Let us assume 200 KV drive voltage. If we assume a voltage of 20KV/cm that gives 10 cm to zero voltage. Then assume 2 MV decelerator voltage. That is 1 meter. So the total radius is 2.1 meter. At 40" per meter (roughly) That is 84" radius or 168" diameter. About 14 ft in diameter for a 100 MWth reactor. Suppose we go to 40KV/cm (about the limit). That would be 1 meter reaction space. About 5 cm to zero voltage. And 50 cm for the decelerator. That would be 1.55 m radius. 3.1 m diameter. About 124" or a little over 10 ft in diameter. So odds are the reactor will be between 10 ft and 15 ft in diameter for a design with direct energy conversion. That would fit on all but the smallest ships.

WB7x Design Issues

Here is my prelim list which gives kind of a broad outline of some of the design issues for WB-7x. This is a strictly first pass effort and is as of yet no where near exhaustive. If you have comments post them.

Power supplies:

Three Alternative Grid supplies
Grid Power 0 - 70KV ~10V steps Capable of modulation @ 10KHz (+/- 5KVpk) for power control 25A continuous. 50A for 3 seconds at reduced or zero modulation due to core saturation (if transformer modulation is used).

Grid Power 0 - 35KV ~5V steps Capable of modulation @ 10KHz (+/- 5KVpk) for reactor power control. 15A continuous. 30A for 3 seconds at reduced or zero modulation due to core saturation (if transformer modulation is used).

Grid Power 0 - 17.5KV ~2.5V steps Capable of modulation @ 10KHz (+/- 2.5KVpk) for reactor power control. 6A continuous. 12A for 3 seconds at reduced or zero modulation due to core saturation (if transformer modulation is used).

PID control designed to keep the Modulation Transformer (if used) unsaturated. Or can be operated open loop.

Ripple less than 100 V at operating current. (that is going to be tough except at high frequencies). Ripple is bad because it spreads the energy.

==========

Magnet power Isolated from Ground to 100 KV
Vacuum Pump Power
Electron gun filament supplies
Electron gun power supplies
Electron gun grid control
24 VDC isolated to 100 KV for the high power control bus rqmts. 1 KW (could be less)
120/240VAC 60Hz 10 KW .6 PF isolated to 100 KV for misc. reactor rqmts

Reaction Control Points:
Coil current
Magnetic Grid Voltage
D-D pressure (will be used to control H in pB11 reaction)
D-D valving (will be used to control H in pB11 reaction)
Vacuum Pump power control
B11 injection control
Electron gun controls

Instruments:
Residual Gas Analyzer
Data Collection and control computer
Coil outlet temperatures
Coil LN2 manifold temperature
Coil LN2 flow rates
Coil current
Laser diagnostics
Neutron counters
Gama counters
Radiation survey instruments
Health physics

Calibration/Quality control materials/data:
Lab Clock for event synchronization

Test procedures:
Item qualifications
System Quals
Reactor Tests

Reactor Systems:
Magnet System
Vacuum Systems
Grid Voltage
HV Safety
LN2 Safety
Coil Energy Safety

Control Bus Issues
Reaction time
Radiation hardness
I like CAN bus for control however, I'm open to suggestions.
No wireless. No crash buses i.e. Ethernet (except for data collection).
Stuff that has to fail safe will be on CAN.

Labratory Procedures
Health Physics
First Aid
Administrative
Scheduling

Labratory Infrastructure
Shop Air
Chilled Water

Update: 28 June 007 2031z
Labratory Infrastructure added
Update: 30 June 007 0536z
Electron gun stuff added