Neutron Transmutation Doping

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
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Richard Hull
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Re: Neutron Transmutation Doping

Post by Richard Hull »

Fission reactors are the only solution to such continuous flux levels on earth.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Dan Knapp
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Re: Neutron Transmutation Doping

Post by Dan Knapp »

Turns out the 2010 Hotta group paper was in Japanese also. There was an English abstract:

Neutron Transmutation Doping (NTD), which is one of the semiconductor manufacturing methods, can produce impurity semiconductor with high quality. The neutron source currently used in the NTD is a nuclear reactor, which has some problems such as to become too old for use. Hence development of a new neutron source, which enables uniform irradiation, is desired. A new Inertial Electrostatic Confinement (IEC) device with a coaxial double cylindrical structure, which is especially designed to be capable of uniform neutron irradiation, was developed. As the feature of the device, it has triple electrode structure which consists of a cylindrical grid cathode between inner and outer anodes. Neutrons are centralized in the center of the device, and uniform neutron flux is obtained there. The device achieved a neutron production rate of 1.5×106 n/s, and uniform neutron flux distribution was provided in the central hole of device. The largest size of the uniform neutron flux area was 35.2% (25 cm) of sample irradiation area in the axial direction, and 54.3% (10 cm) in the radial direction.

As you can see, their neutron production rate was nowhere near what would be needed for NTD.
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Samuel Low
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Re: Neutron Transmutation Doping

Post by Samuel Low »

Interesting... I found the article online too, the one you just shared, Dan. Thank you very much, it sheds light on how far we are from using IEC devices for neutron production!

Richard, do you happen to know the highest record for neutron production in an amateur fusion device? Would be interesting to know how far out a fusor can go even with all the engineering limitations :)
"Physicists are made of atoms." - Michio Kaku
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Richard Hull
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Re: Neutron Transmutation Doping

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Steve Sessleman keeps the records on this, but I think that on this site, 2-3 million neutrons/sec emission (isotropic) is the maximum range, but this is typically only limited by the ultimate HV the fusioneer has to apply to his fusor. (Thus far, this maximum is in the 40-60kv range for amateurs here)

We are limited to D-D fusion, by law in the case of what fusion fuel we can easily aquire and by economics keeping us from using D-3He fuel. I imagine, with a 100kv power supply, an amateur might be limited to under 10 million neutrons/sec (isotropic).

A good, honest evaluation would say that 1 million neutrons/sec is easy to achieve by a determined fusioneer with decent, but not perfect, apparatus provided his power supply could readily reach 40kv and supply a stable 20ma of current at that voltage. Using this same setup, and operational experience, over time, close to 2 million neutrons per second might be possible. Again, the limit here is set by the high voltage supply and limitations of the original insulation within the fusor chamber and wiring.

As I have noted many times here.....At any given degree of perfection of equipment and any given limitations in the applied voltage and current, the maximum performance at this point is solely a matter of operational experience by the amateur fusioneer.

There is some artifice involved in operating a fusor, beyond the physics and the science of it.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Samuel Low
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Re: Neutron Transmutation Doping

Post by Samuel Low »

Thank you Richard, for once again sharing the insight and wisdom. Its truly appreciated.

Artifice is a good word indeed... :)
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Richard Hull
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Re: Neutron Transmutation Doping

Post by Richard Hull »

Thank you for recognizing "artifice" for what it means in relation to a fusor. I often wonder if it is understood at the core level by many here.

The fusor is an item that works due to the physics and scientific principals only!! No art involved at the theoretical level.
However, the operation of a fusor by the human hand is an art. The fusor operates on a thin sliver of gas discharge physics that is a moving target as operation progresses. The human operator is the active hysteresis loop in this operational regime. Learning how to be a human bungee cord within the operational loop is an art. The active and successful operation of a fusor demands artifice.

This artifice can be hinted at in the demo fusor as the operator spends time trying to achieve star mode and observing gas discharge characterisitcs at different levels of evaucation. Moving on to the fusor, ever more critical control is demanded, but the basics should be in place to succeed having already run and studied the demo fusor.

It took me two years of demo use to, finally, do fusion and 2 more to do it well and another 2 to perfect technique. Over this course of time I was out in front and had no forebearers or extensive knowledge base beyond my own reading and hands-on-imperative. Fusor net's informational volume grew as I did and ultimately I learned even more from my betters and more extensively learned that showed up here in the 2004 time frame and to date.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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