Agree? My conception of fusion in WB6.

Discuss how polywell fusion works; share theoretical questions and answers.

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mattman
Posts: 459
Joined: Tue May 27, 2008 11:14 pm

Agree? My conception of fusion in WB6.

Post by mattman »

Hello All,

Here is my conception of fusion in WB6.

If what I have here is incorrect, please speak up.

Here is the machine structure:

Image


This is placed inside a vacuum chamber. Here are the steps for fusion.

1. Pumping down the chamber – making a vacuum (Pressure < 1E-7 torr). There is trace air in there.


2. Electric field between the rings and cage go on. The rings are biased a positive 12,500 volts.


3. Rings are turned on. Each ring has between 20K and 800K AmpTurns. This is a minimum of a ~1,000 Gauss field


4. Electrons are emitted. This is done with four capacitors at the corners. They fly towards the rings, get caught by the B-field and are trapped in the center. They have a maximum energy of 12.5 KeV. They will not be trapped forever.


5. A (-) point in the center forms. That means 1.2 to 1.5 E12 Net Electrons. At Beta = 1 the electron density is one electron in 10^-19 meters of space and the energy looks like this:

Image


6. Deuterium gas is puffed in from a glass tube at room temperature. It is uncharged, so it can reach the rings with no problems. It exchanges energy with the electron cloud. It heats up past 16 eV. It ionizes.


7. The ion forms, sees the - 10,000 voltage in the center and accelerate. The ions heat up to 10 KeV. The energies look like.

Image


The goal is to heat the ions. They are heated as the electric field does work on them. For many reasons, this works best, when the electrons are very cold, very negative and very tightly held together.


8. For every fusion reaction that does not occur, a (+) is left in the center. Over time, this will kill the machine. Hence, we want every ion injected to fuse, right away.


If you agree with this, we can translate this info into a YouTube Film.

hanelyp
Posts: 2261
Joined: Fri Oct 26, 2007 8:50 pm

Re: Agree? My conception of fusion in WB6.

Post by hanelyp »

mattman wrote:Here is the machine structure:
Looks reasonable.
This is placed inside a vacuum chamber. Here are the steps for fusion.
...
4. Electrons are emitted. This is done with four capacitors at the corners. They fly towards the rings, get caught by the B-field and are trapped in the center. They have a maximum energy of 12.5 KeV. They will not be trapped forever.
Terminology quibble: the electrons are fed through cathodes at the corners. Those cathodes I understand were fed from capacitors outside the vacuum box on WB-6.
5. A (-) point in the center forms. That means 1.2 to 1.5 E12 Net Electrons. At Beta = 1 the electron density is one electron in 10^-19 meters of space and the energy looks like this:

Image
Where within the wiffleball volume is this? Center, edge, overall?
7. The ion forms, sees the - 10,000 voltage in the center and accelerate. The ions heat up to 10 KeV. The energies look like.

Image
The ion energy there looks like the center. Near the edge there would be similarly narrow spread at lower energy.
8. For every fusion reaction that does not occur, a (+) is left in the center. Over time, this will kill the machine. Hence, we want every ion injected to fuse, right away.
As a rule an ion will need many passes through the core to fuse.
An ion which does not fuse on it's first pass through the center is typically scattered by collision with another ion. Ions which are left with lower energy have a chance to recover their energy with later collisions. Ions with slightly upscattered energy also have a chance to give away their excess energy by additional collisions. Highly upscattered ions are weakly confined by the wiffleball magnetic field, gaining numerous additional passes across the plasma to be downscattered.
The daylight is uncomfortably bright for eyes so long in the dark.

KitemanSA
Posts: 6179
Joined: Sun Sep 28, 2008 3:05 pm
Location: OlyPen WA

Re: Agree? My conception of fusion in WB6.

Post by KitemanSA »

My recollection is more like this.
1 ) Open the copper switch.
2 ) Ensure gas solenoid switch is closed. (tank pressure < 1E-6 torr)
3 ) Enable all recording instrumentation.
4 ) Charge section of gas tubing to desired value (usually 300mtorr).
5 ) Activate heating current for emitters, via Siemens switch.
6 ) Enable the Hipo power supply, and charge capacitors to desired voltage.
7 ) Disable Hipo, via “Stop Charge”, while leaving caps charged.
8 ) Turn on magnetic field to desired value, via battery bank IGBTs.
9 ) Close copper switch, thus allowing emitters to start emitting electrons
10) Close relay for gas solenoid; gas into system, discharge cap bank.
11) Turn off uncooled magnets, once sure caps have discharged.
12) Secure emitters, gas line, high voltage, and stop recording data.

D Tibbets
Posts: 2775
Joined: Thu Jun 26, 2008 6:52 am

Re: Agree? My conception of fusion in WB6.

Post by D Tibbets »

Your concept is fairly accurate with these corrections, based on my understanding.

The electron guns are 12 volt automotive light bulb filaments and are fed high current but low voltage (~12 volts from batteries). The high voltage on the surface of the magrid is driven from ~ 12,000 volt charged capacitors. The high current flow to the magrid surface needs to match the current flow through the e-guns, otherwise the voltage on the magrid would drop. This is why EMC2 resorted to using high voltage capacitors. They could not afford the power supplies that could provide the high voltage AND high current. It is easy to get high voltage or high current, but both at the same time becomes challenging (expensive). According to the reports, the 12,000 volts accelerated the low voltage electrons to ~ 1,000 volts- 10,000 eV energies. There is some inneficiency fo the full 12,000 V energies are not attained. This 10KeV was the energy of the electrons in the best WB6 test runs. I still don't know where you are getting the 2.5 KeV values. Perhaps from other machines like WB5. or earlier where they were having difficulty reaching the deep potential wells obtained in WB6.

The electron temperature average was 10 KeV at their maximum, the potential well depth was 10,000 volts and the ion energies were 10 KeV at their maximum. The numbers are the same and has to be. The electron temperature (average) equals the ion temperature average. The distribution of these energies at various radii within the machine are dynamic and generally in opposite directions. Ions zero eV at the edge and 10 KeV at the center, while the opposite is true for the electrons. That is why magnetic confinement only applies to the electrons. On the edge the electrons have a large outward velocity that has to be turned by the magnetic field. The ions stop on their own due to the centrally directed potential well for the ions (reverse of the potential well for the electrons).

The current that drives the electromagnets is provided by batteries at perhaps ~ 24 volts. My recollection was that there were 200 windings inside the cans and were fed ~ 1000-2000 amps. These wires are insulated from each other with the varnish on the wires and the whole wire bundle is isolated from the high voltage magrid can surface with several layers of mylar (probably yilar as it is a very good insulator). The amp turns were ~ 200 to 400 thousand. This may have been different in WB4,5, and possibly WB7.

Bussard said that the ions have to make ~ 10,000 passes befor there is a good chance of fusion. This number of course changes with density and temperature. I don't know if Bussard was refering to a 30 cm machine with a density of ~ 10^19 ions per M^3 and radius of 30 cm and temperature of ~ 10 KeV like in WB6 or the projected demo machine at 3 meters and a density of ~ 10^22 ions/ M^3 and temperature of ~ 80 KeV, but the relationships would be similar.

At 10 KeV the Coulomb collision cross section is ~ 1 million times greater than the D- D fusion cross section. At 80 KeV this ratio changes to ~ 1000 Coulomb collisions per fusion collision (for D-D fuel, D-T fuel ratio would be closer to 10 at 50 KeV). From this information you can calculate possible MFP till Coulomb collision distance to fusion collision distance. . Assume a conversant meter diameter machine. 10,000 passes would be 10,000 Meters traveled before fusion, and at 80,000 eV the Coulomb collision MFP would be ~ 1000 times less or ~ 10 meters. This suggests that the Coulomb collision MFP is greater than the machine diameter, so ion annealing could be maintained. Of course this may not accurately represent the conditions based on density, but the ratios should be maintained. If the density is increased 10 fold, both the fusion and coulomb collision MFP would decrease ~ 100 fold (collisions scale as the square of the density). This may set an upper limit on the density that can be obtained and this would effect the size of the machine also. Bussard worked all of these relationships along with the dynamic conditions within the magrid space and h,e at least, felt that there was no show stoppers.

Note that a distance to fusion in a Tokamak may be around several hundred thousand Kilometers. If the Polywell can obtain advertised densities ~ 100 to 1000 times greater, the distance traveled till fusion occurs would be reduced to ~ 1 to 10 KM. Again this is a check of the reasonableness of the claimed physics. The shorter distance translates into proportionately less confinement times required to meet the Lawson criteria, the higher operating average ion energy helps further). This is why the Polywell with seemingly dismal energy confinement times of a few milli seconds can outperform a Tokamak with confinement times measured in 100s of seconds., and do so with D-D fuel instead of the much more problematical D-T fuel. At least this is the case provided it can be made to work. There are all sorts of engineering issues that have to be resolved.

Dan Tibbets
To error is human... and I'm very human.

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