The D-D neutron energy of the Mk0 device is 2.5 MeV.
The same neutron energy can be expected for the NSD NG Mk1 device.
D-T ~14 MeV neutron energy has been indicated by activation tests.
Development tests were conducted in a laboratory of the Physics Department of the University of Liverpool.
An output neutron flux dosage equivalent to a point source strength of ~1 x 107 n/s was a preliminary measurement.
Following a relocation to a test facility with more than adequate shielding, intensive tests were conducted over many weeks.
Achievements:
The measurements are provisional and subject to validation by the Physics Department of the University of Liverpool.
The primary aim was to reduce specific power consumption.
Initially more than 2 kW was required for ~1 x 107 n/s. This has so far been reduced to 800 W.
~2 x 107 n/s DD 2.5 MeV reached with a long electrode. (Limited by the available power supply)
~1 x 107 n/s DD 2.5 MeV reached with a short electrode at 95 kV and 10.0 mA
Experiments with a short electrode showed the scaling of the neutron emission with electrode length and increase power input to increase the total neutron output.
The engineering limits are associated with the electrode temperature and chamber heat dissipation. So far the achievement of 1 x 108 n/s (DD) is quite feasible with a suitable power supply, reaction chamber geometry and air cooling sub-system. (see geometry)
~14 MeV neutron production from the D-T reaction was tested in a Mk0 device in a German commercial laboratory. The gain over D-D at similar conditions was a factor of ~80.
The demonstrator unit was then installed within the laboratory of the Aachen University of Applied Sciences, Department of Energy and Environmental Protection Engineering, Nuclear physics, Nuclear Engineering, in Juelich. Brief tests confirmed the performance.
Measurements in the laboratory of the Mannheim University of Applied Sciences used thermal neutron counting methods.
Two different neutron area dosimeters measured the neutron field at distances 1 to 2 m from the NSD neutron generator fitted with a short electrode. The dosage measurements were similar. With the assistance of Dr. Klett of Berthold Technologies, the calibration data of a LB 6411 Neutron Probe was used to determine the neutron source emission rate at a reference voltage and current.
A customer has also performed measurements using a different thermal neutron detection and counting method. Secondary or scattered neutrons from the surrounding walls, ceiling and floor were shielded from the detector so that the flux was mostly from the direction of the neutron generator. A crane was used to suspend the neutron generator above a table in order to minimize the effects of surrounding structures. These measurements were in good agreement with the neutron dosimeters.
In both these measurement campaigns a reference 252Cf source was available.
A near field survey will be conducted when yield has been maximized.
Longer tests over several days were conducted during a quick demonstration of PGNAA by Dr. A. Nordlund of Chalmers University, Nuclear Engineering. The short electrode DD neutron generator was operated at 1x106 n/s in a cycle of 5 minutes on, change the moderator test set-up, another 5 minutes on and so on with excellent repetition.
After a running-in phase, the output is very stable and repeatable.
An improved (high temperature) electrode is now installed at the Hochschule Mannheim, University of Applied Sciences, Department of Chemical Engineering and Process Engineering, Prof. Dr. Erich Fosshag. This unit has been operated at up to 8 x 106 DD n/s with very smooth, stable and repeatable output; even in the semi-automated mode. Full automated regulation will further reduce the small swing of output caused by the available regulation system.
The automated neutron generator can be operated in pulsed mode (to 10 kHz).
The pulsing characteristics and mode options are being developed.
A very compact pulsed power supply module technology has been selected.
Please contact us to discuss your requirements.