Single circuits generate nuclear reactions

[hartiberlin]

Hi Dr. Feynman,
still 2 questions:

what was the height of the graphite rod in the experiments ?

What was the distance of the 2 magnets ?

Many thanks

[Yucca]

@Koen

I think I guess we are trying to make a 'beta battery' in the sense where the beta particles strike a surface, perhaps displacing charge, in order to create a potential which gives us nice high usable current. At present, we are losing many beta particles by letting them fly past our collector, and consequently we are not getting high enough current density on the output (way below theoretical maximum), although this process does appear to exceed COP=1.  Although we are able to get 'runaway' , and this is great for lab fun and excitement, it is not as useful for a generator to run your house.

Primarily we need two things

1) An efficient method of capturing and converting beta rays into usable voltage and current.
2) A method of PWM feedback which we can connect the output back to the input without the threat of 'runaway' condition.

Feynman,

Congratuliations on your succesful replication!!!

I'm not sure about best beta collection method, but I am sure on the best way for you to setup PWM control, I used to work as a realtime embedded system engineer programming 68HC11 and a little ATMega stuff:

Use your arduino board, put a small cureent sensing toroid around the main output and feed that as input to ADC pin on arduino (probably need to buffer it with opamp). Then you can put any control algorithm into arduino that you require to control this beast by outputing PWM from arduino to drive your IGBT. The beauty of software control as I'm sure you know is rapid development and evolution of the control algorithm without having to swap out parts etc.

[Yucca]

BE SAFE EVERYONE:

Quote from wiki:
"Beta particles are able to penetrate living matter to a certain extent (radiation intensity from a small source of radioactive material decreases as one over the distance squared) and can change the structure of struck molecules. In most cases such change can be considered as damage with results possibly as severe as cancer and death. If the struck molecule is DNA it can show a spontaneous mutation. If this mutated DNA is in gametes the mutation may be passed to new generations. By far most mutations are considered genetic defects, it is not proven if mutations caused by beta particle absorption could lead to positive evolution."

(Source: http://en.wikipedia.org/wiki/Beta_particle#Health)

[Feynman]

still 2 questions:

Anytime Stefan

what was the height of the graphite rod in the experiments ?

It was 1/2" diameter pure carbon rod of several inches in length, although Dr. R suggests you should not exceed 2" for rod length because of nuclear shielding effects begin to reduce conversion efficiency.

What was the distance of the 2 magnets ?

From my understanding, the magnets are placed opposed in the center of the rod to ensure the magnetic flux passes through the carbon, and so the magnetic flux aligns the dipoles of the internal carbon atoms to be parallel or antiparallel with the subsequently applied E-field (pulse discharge).  And that is, of course, how you get your beta.   You will not get the beta without applying the strong magnets.    In any case,  I think the distance of the magnets is also several inches apart, pressed directly up against the ends of the carbon rod.   I will confirm this as soon as possible.

I wish I had more details specifications for you guys, but I do not have them at the moment. All I know is this works and provides a massive amount of beta rays, we have had a somewhat remarkable 'runaway' reaction where output connected back to input, we also have what appears to be COP>1, but I do not want to be making too many claims too early. We are having difficulty in betavoltaic conversion. This problem needs to be solved by some sharp minds.  This is also in such early stages of the technology there is much that we do not know.  My own experimental setup is not yet complete.  I promise I will post my own pictures as soon as possible.

What we need now is device replications and creative methods of betavoltaic conversion.  We also need fusing, kill switch, and PWM control so we can safely re-attempt self-powering operation.

[Feynman]

@Yucca

Yes, beta is ionizing but it falls off very rapidly in air.   So the level of beta few feet back is MUCH lower, if detectable at all  (it decreases with 4 PI r^2 or higher).  Just put up some aluminum shielding and have some experience with high voltage.

I was also thinking about the PWM, and using the Arduino's ADC chip to monitor the feedback, using an attenuator if necessary..  I am a big Atmel fan as well.    I think I will also be using this method.    I think it will be easier to figure out the control circuitry rather than the most effective betavoltaic conversion , but then again maybe that's just me.  Thank you for your thoughts.