Study of the neutron pulse regularity of a small dense plasma focus device by time of flight measurements

Plasma foci are well know to be efficient neutron generators, with a great potential for immediate applications. For this purpose, it is particularly important to assess the uniformity of their behaviour, which strongly depends on the geometry details and the materials used in their construction. It has been established that there are competing mechanisms in the neutron generation, that yield both isotropic and anisotropic components. However, the latter, which may be associated to the generation of axial ion-beams has been found to contribute no more than 30the total neutron yield, and less than 10particular device. As a matter of fact, measurements of the ratio of head-on and side-on neutron fluxes have been found to be grossly misleading, since they may be extremely large due to very pronounced anisotropic components, even though they may actually contribute less than 10neutron yield. The isotropic component, on the other hand, can be reasonably described by thermonuclear models, and within the experimental error, allowed by the regularity of the device behaviour, can be properly characterised by side-on measurements. The purpose of this work is to study the regularity of the neutron emissions from a small dense plasma focus (5kJ at 37kV) [1], analysing the time of flight signals from three, side-on, on-line, scintillation detectors. [1] F. Castillo, J.J.E. Herrera, J. Rangel, A. Alfaro, M.A. Maza, V. Sakaguchi, G. Espinosa and J.I. Golzarri, "Neutron Anisotropy and X-ray Production of the FN-II Dense Plasma Focus", Brazilian J. Phys. Vol.32 (2002) 3-12.