Neutron Generators: Build, Usage, Pictures, Plasma Focus

[JB Mandengue]

a) I need a simple description of how a Neutron Generator is built and how it works.

b) Where can I see a picture of what a Neutron Generator looks like?

c) What is a Plasma Focus (PF) Neutron Generator?

d) Is PF the only type of Neutron Generator or are there other types?

 

[Astronuc]

Is this a homework problem?

Two common methods would the (d+t) reaction using accelerated deuterons on a tritiated target, and an (alpha, Be) reaction in which alpha particles from a radionuclide of a Pu, Po or Ra isotope bombard Be nuclei.

There are other methods.

 

[JB Mandengue]

Thanks for the answer. I am familier with isotopic sources using the (alpha,n) reaction. It is the (d+t) you mention that I don't understand. How are the deuterons accelerated? Is he (d+t) a portable devise?
BTW this is not a home work problem.

 

[Astronuc]

Thanks for the answer. I am familier with isotopic sources using the (alpha,n) reaction. It is the (d+t) you mention that I don't understand. How are the deuterons accelerated? Is he (d+t) a portable devise?
BTW this is not a home work problem.

For the d+t reaction, there are two possibilities. One is to electrostatically accelerate deuterons across a potential difference of a few keV. The deuterons then stike a triton (nuclear of tritium) which could be in the form of a metal hydride. This is the principle of a neutron howitzer.

Another possibility is to heat a mixture of deuterium and tritium gas until is ionizes into a plasma. At sufficient temperature (with a reasonable density) deuterons and tritons will fuse, and in fact one might obtain d+d fusion, with production of He³+n or t+p. This is the principle behind magnetic confinement (low density) and intertial confinement fusion (high density).

The third alternative is a hybrid of the other two, using electrostatic fields to accelerate deuterium/tritium gas into a central confinement volume in the presence of a magnetic field.

Example - http://www.physics.ucla.edu/icnsp/PDF/bromley.pdf

 

[JB Mandengue]

Thanks again. Thanks so much. If I may ask further. Is a battery connected to the Neutron Generator to create the potential difference that accelerates the deuterons? Do you have a picture of one of these devises?

 

[Astronuc]

Thanks again. Thanks so much. If I may ask further. Is a battery connected to the Neutron Generator to create the potential difference that accelerates the deuterons? Do you have a picture of one of these devises?

Batteries are not used. Rather high voltage power supplies would be used.

Here is an article with a schematic.
http://fsl.ne.uiuc.edu/IEC/Miley_Radio.Nuc.Chem(2005).pdf

Fusor time arrangement
http://www.absoluteastronomy.com/topics/Inertial_electrostatic_confinement

A patent - Neutron tube comprising an electrostatic ion source
http://www.freepatentsonline.com/5152956.html

 

[JB Mandengue]

Thank you Astronuc. The principle and method of operation is now clear to me. With the drawings you indicated, I can visualize the equipment. I guess the only question left now is how "Plasma Focus" fits into all this.

 

[Bob S]

Compact pulsed D-T neutron generators are used among other things for oil well logging. See picture in:
http://www.thermo.com/com/cda/resources/resources_detail/1,,11801,00.html
The D-T neutron production threshold is about 50 KeV, and the neutron energy is about 14.1 MeV.
Bob S

 

[JB Mandengue]

Thank you Bob. I have just read the thermo article. very informative - especially the simple sketches and the photo which shows exactly how the NG looks.