Neutron diagnostics is applied to a powerful deuterium beam. The diagnostic
method is based on the recording fluxes of fast neutrons generated in the
D+ + D --> n + He-3 fusion reaction during the interaction of beam deuteron
s with deuterium atoms of the residual gas in the chamber. A neutron detect
or based on a polystyrene hydrogenous scintillator is used. This detector a
llows one to measure incident neutron fluxes with intensities ranging from
10(3) to 2 x 10(5) neutron/s with a measurement time of 4 ms. The observati
on shows that the count rate of neutrons increases during the beam pulse, w
hich is caused by the increasing pressure of deuterium in the chamber. The
measured values of the neutron fluxes correspond well with the calculated d
ata. (C) 2000 Elsevier Science B.V. All rights reserved.