Preliminary neutron experiments with the PF-1000 plasma-focus facility
M. Scholz · R. Miklaszewski · M. Paduch · M.J. Sadowski · A. Szydlowski · K. Tomaszewski
Summary and citation · read the original at the source
In one page
PF-1000 is a plasma focus: a big capacitor bank dumped down a pair of coaxial electrodes, driving a sheet of current that sweeps deuterium gas ahead of it and then collapses onto the axis into a dense, self-holding pinch that makes fusion neutrons. Marek Scholz and his colleagues at Warsaw report the first neutron experiments on the rebuilt machine. They photographed the current sheet with high-speed cameras through a narrow radial slit and worked out how fast it collapsed. They counted the neutrons with four silver-activation detectors placed at different angles to the electrode axis, so they could see whether the emission was directional. Two findings shape the rest of the programme. Neutron output does not simply rise with the voltage you charge the bank to: at each gas pressure it climbs to a peak and then falls again. And the neutrons seen looking back up the axis carry a little less energy than a deuterium reaction at rest would give — the signature of nuclei already moving when they fuse.
Why it matters hereChapter 9 is about plasma that organises itself into a dense structure and holds together long enough to do work, and the plasma focus is the industrial-scale worked example — here with the collapse speed measured on film. Chapter 12 wants the fusion output measured honestly, and this is the paper where PF-1000’s yield curve and its directional signature were first laid down, before the machine reached full energy.
What it claims
01This is the first neutron-emission campaign carried out on the modernised PF-1000 facility. Everything reported here is the machine’s starting point, not its ceiling — the full-energy megajoule results came later.Abstract, first sentence
Published and peer-reviewed02Current sheath dynamics were investigated with high-speed cameras. The compression velocity was determined from smear pictures taken through a narrow radial slit — a technique that turns the collapse into a streak on film, whose slope is the speed the sheet moves at.Abstract, second and third sentences
Published and peer-reviewed03Total neutron yield and the anisotropy of the angular distribution were measured with four silver-activation counters placed at different angles to the electrode axis. Four detectors at four angles is what makes the anisotropy a measurement rather than an inference: if the neutrons came from a simply hot plasma they would arrive equally in every direction.Abstract, fourth sentence
Published and peer-reviewed04For each initial deuterium filling pressure, raising the charging voltage increases the neutron yield up to a maximum, and raising it further makes the neutron emission decrease. The yield curve turns over — more stored energy is not automatically more fusion, and the optimum is a pairing of pressure and voltage rather than a single knob. The highest yield registered in this campaign was 2 times 10 to the eleventh neutrons per shot.Abstract, fifth and sixth sentences
Published and peer-reviewed05The neutron emission anisotropy appears lower than that registered in other plasma-focus experiments — so on this machine the emission is closer to even across angles than the plasma-focus literature had led the authors to expect.Abstract, seventh sentence
Published and peer-reviewed06What to watch: the neutron energy spectra measured with a scintillating probe looking upstream are shifted toward lower energy, 2.2 to 2.3 million electronvolts, against the 2.45 million a deuterium-deuterium reaction gives between nuclei at rest. A downshift seen from upstream is what directed ion motion away from the probe produces. The later review of the same machine at full energy reports a maximum upstream energy of 2.95 million electronvolts instead, so the two campaigns sit on opposite sides of the rest value. What would settle the picture is a spectrum taken upstream and downstream on the same shots, with the ion beam diagnostics recording alongside.Abstract, final sentence
What to watch
The way in
https://doi.org/10.1109/tps.2002.1024279Published as IEEE Transactions on Plasma Science, volume 30, issue 2, pages 476 to 481 (April 2002). The record is closed access: Unpaywall, OpenAlex and Semantic Scholar all report no open copy anywhere, and the only licence on the deposit is IEEE’s own. No text of the article is reproduced here. This sheet was written from the authors’ own abstract as deposited by IEEE and read through OpenAlex on 2026-09-08; every claim below is drawn from that abstract alone and located to it. Two notation conventions in the deposited abstract are expanded here for readability: D/sub 2/ is deuterium gas, V/sub 0/ is the capacitor bank charging voltage.
How to cite it
M. Scholz, R. Miklaszewski, M. Paduch, M.J. Sadowski, A. Szydlowski, K. Tomaszewski (2002) Preliminary neutron experiments with the PF-1000 plasma-focus facility. doi:10.1109/tps.2002.1024279
Where it sits in the curriculum
Plasmoids, charge clusters and the orbsLattice confinement fusion