Historical research guide · 1098 · 2008
Activities Study of Short-lived Radioisotopes with a Filippov-type Plasma Focus
Alireza Asle Zaeem · S. Mahmood Sadat Kiai · Mahmood Sedaghatizade · Shirin Adlparvar · Shahab Sheibani
In one minute
A plasma focus is a simple, violent machine. A capacitor bank dumps its charge into a low-pressure gas, a sheet of current sweeps across the electrodes and collapses onto the axis, and for a few tens of nanoseconds there is a pinch of plasma dense and hot enough to fuse. Alireza Asle Zaeem and colleagues, at Khajenasir University of Technology and the Atomic Energy Organization of Iran, ask that pinch to do something other than make power. Add a trace of a second gas to the deuterium, and the deuterons streaming out of the pinch will transmute it. Their calculations model the Dena device, a Filippov-type plasma focus in Tehran, running as a breeder of short-lived radioisotopes: boron-10 struck by a deuteron becomes carbon-11, and nitrogen-14 becomes oxygen-15 — the two short-lived positron emitters that hospitals use for PET scanning. They work out the activities for capacitor bank energies from twenty to ninety kilojoules and repetition rates from one to ten shots a second.
Connection
Chapter 18 collects the machines that make fusion conditions in a room rather than in a reactor hall, and the plasma focus is the smallest and most-copied of them. This paper is a good demonstration of why that matters beyond energy: the same nanosecond pinch that yields neutrons is a compact, pulsed particle source, and if it can breed medical isotopes on a bench then the device has a second economy of its own long before it produces net power.
From the source
What a plasma focus is, in the paper’s own opening: a device characterised by a short-lived dense and hot plasma pinch, produced by radial compression and electromagnetic acceleration of the current sheet.Abstract, first sentence
The pinch has two useful phases, not one. Over a period of typically a few tens of nanoseconds it goes through a compression phase, which is thermal, and an expansion phase, which is non-thermal or beam-target — and between them these provide the conditions necessary for high nuclear reaction rates. The beam-target phase is what makes the device an accelerator as well as a hot plasma.Abstract, second sentence
With an appropriate gas admixture at a desirable pressure, those processes generate short-lived radioisotopes, and the level of activity obtained depends on the design and operational parameters of the machine rather than on anything intrinsic — which is what makes the yield an engineering variable to be optimised.Abstract, third sentence
The two reactions studied are deuteron-induced: boron-10 plus a deuteron gives carbon-11 plus a neutron, and nitrogen-14 plus a deuteron gives oxygen-15 plus a neutron. The machine modelled is the Filippov-type plasma focus Dena, used as a breeder, over capacitor bank energies from twenty to ninety kilojoules and repetition rates from one to ten hertz.Title; Abstract, fourth sentence
The operating point chosen for the calculation: the admixture gas pressures of boron-10 and nitrogen-14 were each taken to be approximately five hundredths of the initial working pressure, with the device set at its optimum neutron yield regime. The isotope breeding is therefore treated as a trace addition to a machine already tuned for neutrons, not as a separate mode of operation.Abstract, fifth sentence
What would settle it. The paper presents the results of simulated theoretical work rather than a measured activity, so the outstanding measurement is the obvious one — the activity actually bred on Dena, or on another Filippov-type focus, across that same range of bank energies and repetition rates, compared against the computed curves.Abstract, fourth and sixth sentences
The way in
https://doi.org/10.1007/s10894-008-9164-zHow to cite it
Alireza Asle Zaeem, S. Mahmood Sadat Kiai, Mahmood Sedaghatizade, Shirin Adlparvar, Shahab Sheibani (2008) Activities Study of Short-lived Radioisotopes with a Filippov-type Plasma Focus doi:10.1007/s10894-008-9164-z