The original concept was developed in 1954 by N.V. Filippov, who noticed the effect while working on early pinch machines in the USSR.
In contrast, z-pinch systems generally use a single cylinder, sometimes a torus, and pinch the plasma into the center.
[2] Pinch-based devices are the earliest systems to be seriously developed for fusion research, starting with very small machines built in London in 1948.
Due to the Lorentz force, this current creates a magnetic field that causes the plasma to "pinch" itself down into a filament, similar to a lightning bolt.
[citation needed] During experiments on a linear pinch machine, Filippov noticed that certain arrangements of the electrodes and tube would cause the plasma to form into new shapes.
The dense plasma column (akin to the Z-pinch) rapidly pinches and undergoes instabilities and breaks up.
The intense electromagnetic radiation and particle bursts, collectively referred to as multi-radiation occur during the dense plasma and breakup phases.
When operated using deuterium, intense bursts of X-rays and charged particles are emitted, as are nuclear fusion byproducts including neutrons.
For nuclear weapons applications, dense plasma focus devices can be used as an external neutron source.
Thus if we have a peak current of 180 kA we require an anode radius of 10 mm with a deuterium fill pressure of 4 Torr (530 Pa).
The above example of peak current of 180 kA rising in 3 μs, anode radius and length of respectively 10 and 160 mm are close to the design parameters of the UNU/ICTP PFF (United Nations University/International Centre for Theoretical Physics Plasma Fusion Facility).
, where E is the energy stored in the capacitor bank and a is the anode radius, for neutron-optimised operation in deuterium the value of this critical parameter, experimentally observed over a range of machines from tens of joules to hundreds of kilojoules, is in the order of
This network produces research papers on topics including machine optimization & diagnostics (soft X-rays, neutrons, electron and ion beams), applications (microlithography, micromachining, materials modification and fabrication, imaging & medical, astrophysical simulation) as well as modeling & computation.
The network was organized by Sing Lee in 1986 and is coordinated by the Asian African Association for Plasma Training, AAAPT.
A simulation package, the Lee Model,[11] has been developed for this network but is applicable to all plasma focus devices.
The code typically produces excellent agreement between computed and measured results,[12] and is available for downloading as a Universal Plasma Focus Laboratory Facility.
Among these machines is one with energy capacity of 1 MJ making it one of the largest plasma focus devices in the world.
The program operates six Plasma Focus Devices, developing applications, in particular ultra-short tomography and substance detection by neutron pulsed interrogation.
The thermodynamic model was able to develop for the first time design maps combining geometrical and operational parameters, showing that there is always an optimum gun length and charging pressure which maximize the neutron emission.
Currently there is a complete finite-elements code validated against numerous experiments, which can be used confidently as a design tool for Plasma Focus.
In Chile, at the Chilean Nuclear Energy Commission the plasma focus experiments have been extended to sub-kilojoules devices and the scales rules have been stretched up to region less than one joule.
Several groups proposed that fusion power based on the DPF could be economically viable, possibly even with low-neutron fuel cycles like p-B11.
The feasibility of net power from p-B11 in the DPF requires that the bremsstrahlung losses be reduced by quantum mechanical effects induced by an extremely strong magnetic field "frozen into the plasma".
Another advantage claimed is the capability of direct conversion[broken anchor] of the energy of the fusion products into electricity, with an efficiency potentially above 70%.
[25] On November 14, 2008, Lerner received funding for continued research, to test the scientific feasibility of Focus Fusion.
[27] On January 28, 2011, LPP published initial results including experimental shots with considerably higher fusion yields than the historical DPF trend.
Fusion yield doubled compared to other plasma focus devices with the same 60 kJ energy input.
In addition, mean ion energy increased to a record of 240 ± 20 keV for any confined fusion plasma.