Let’s get this up and running!

And don’t forget to join us on Gameful for further collaboration.

Zotero Focus Fusion Group

I have added a random selection of papers from my library - some more relevant that others.

This is a duplication of some of the papers listed on this site, but it seems an easy to manage system.  I can add others as admins to the group so you can all add your own selections of relevant papers.

Did you find it useful?  Have you tried publishing?  How was your experience?  What changes can we make and what other features would you like to make this a more useful experience?

Discuss here.

I will probably be going to the IOP Annual Conference on Plasma Physics
http://plasma10.iopconfs.org/

which is being held this year in Windermere from 29 march- 1April

James

Chris Hagen of National Security Technologies announced for the first time work that has been ongoing for a few years in Las Vegas Nevada to use large DPFs as neutron sources for testing purposes. NSTec had built in 2008 a 500 MJ DPF called Tallboy that produced 3 MA of peak current and is now testing a 1 MJ DPF that is expected to generate over 4 MA of peak current, which will make it the most powerful in North America, and possibly in the world. The work, while unclassified, was funded by a Department of Energy National Strategic Security program that had previously limited public disclosures. Tallboy achieved a maximum neutron yield of 6x10^11 with deuterium, when charged with 250 kJ. Currently the new 1 MJ Gemini machine uses electrodes with the following dimensions: anode radius 7.5 cm, cathode radius 10 cm, insulator length 7.5 cm and electrode length 50 cm, which makes it intermediate in size between the larger PF-1000 in Warsaw and Focus-Fusion-1 in New Jersey.

Per Eric Lerner:

Several of the presentations concentrated on the questions of small structures in the DPF—filaments and hotspots or plasmoids—testing the model of the DPF process first elaborated in the 1970’s by Winston Bostick and Victorrio Nardi. While controversial for many years, this model is now becoming central to much of the research in the field, as was demonstrated at this conference.

Reporting on work at the PF-1000 using laser interferometer, P.Kubes et al described hot spots 1 cm in radius with densities of up to 10^19 particle/ cm^3.  While this is considerably larger than the plasmoids described in the Bostick-Nardi theory, there was other evidence that in fact the plasmoids in this machine are much smaller. E. Składnik-Sadowska et al showed with ion pinhole cameras and aluminum filters that the ion beams with energies above 700keV are narrowly focused to close to the pinhole size of 0.5 mm radius, implying that the beam originated from a similarly small region. That group also observed microbeams only 3 microns in radius.

The PF-1000 is rerunning with an anode radio of 11.5 cm, cathode radius 20 cm and electrode length of 48 cm.

Kubes also reported similarity small hot stops from the S-300 device at the Kurchatov Institute in Moscow, with 1 mm radii and density of 10^20/cm^3. W. Stepniewski also studied filamentation in a 2-D MHD simulation.

Finally, S.K.H Auluck asked the question: what generates the angular momentum in the DPF pinch? This is the same question that led to LPP’s idea that the initial magnetic field along the axis, supplied by the earth, is magnified to provide the angular momentum. Auluck answers differently, attributing the angular momentum to the creation of what is called a Turner Relaxed State.

APPLIED PHYSICS LETTERS 95, 151503 (2009) published online 15 October 2009

Abstract:  Plasma focus research in the direction of fusion energy faces the limitation of observed neutron saturation; the scaling deteriorating as storage energy E0 increases toward 1 MJ. Numerical experiments confirm this deterioration of scaling. This paper points out that the cause is the dynamic resistance of the axial phase that is constant for all plasma foci. This dynamic resistance dominates the circuit as capacitor bank surge impedance becomes insignificant at large E0, causing current, hence neutron “saturation.” With the cause thus identified, the paper also suggests a cure; to operate plasma focus at high voltages and with current-step technology.

Summary by Lerner:

Professor Lee provides a theoretical study of why earlier DPF experiments showed an apparent maximum or saturation of neutron production and how this could be overcome. Using his own group’s one-dimensional simulations of the run-down and pinch of DPFs, he shows that if capacitor banks are just built larger, with more capacitance, with longer and longer pulses, DPF electrodes will also get longer. This in turn increases the inductance, a measure of how much magnetic energy is generated by the currents between the electrodes. With more and more of the bank’s energy going to supply this magnetic energy, it becomes impossible to increase peak current beyond around 4 MA, even with huge capacitor banks of 45 MJ or more. Lee proposes the solution to this dilemma is to use capacitors operating at higher voltages.  This can increase peak current without increasing pulse length.

Abstract:  Dynamic plasma pinches occur in a variety of devices, as Z -pinches and plasma focus. In this paper, a lumped parameter model of a dynamic plasma pinch produced in a plasma focus discharge is presented. The model is based in Von Karman approximations of the radial density and velocity profiles, which leads to the reduction to a system of ordinary differential equations describing the dynamic evolution of the pinch compression and expansion. The model was coupled with a fusion kernel to produce an estimate of the neutron yield per pulse. The calculations were tested against available data of the pressure–yield curve of seven experimental devices ranging from 1 to 250 kJ, showing excellent agreement, particularly regarding the curvature of the pressure–yield curve.