Kunihito Yamauchi

Pulsed Operation of a Compact Fusion Neutron Source Using a High-Voltage Pulse Generator Developed for Landmine Detection

Abstract Preliminary experimental results of pulsed neutron source based on a discharge-type beam fusion called Inertial Electrostatic Confinement Fusion (IECF) for landmine detection are presented. In Japan, a research and development project for constructing an advanced anti-personnel landmine detection system by using IECF, which is effective not only for metal landmines but also for plastic ones, is now in progress. This project consists of some R&D topics, and one of them is R&D of a high-voltage pulse generator system specialized for landmine detection, which can be used in the severe environment such as that in the field in Afghanistan. Thus a prototype of the system for landmine detection was designed and fabricated in consideration of compactness, lightness, cooling performance, dustproof and robustness. By using this prototype pulse generator system, a conventional IECF device was operated as a preliminary experiment. As a result, it was confirmed that the suggested pulse generator system is suitable for landmine detection system, and the results follow the empirical law obtained by the previous experiments. The maximum neutron production rate of 2.0×108 n/s was obtained at a pulsed discharge of -51 kV, 7.3 A.

Research and Development of the Humanitarian Landmine Detection System by a Compact Fusion Neutron Source

Results of 5 years task are described on the research and development of the advanced humanitarian landmine detection system by using a compact discharge-type fusion neutron source called IECF(inertial-electrostatic confinement fusion) device and dual sensors made of BGO and Nal. With 107 neutrons/s stably produced in CW mode, 10.8 MeV, gamma rays from (n, gamma) reaction with nitrogen atoms in the explosives (explosive simulant in our study) are measured for two kinds of explosives(TNT, RDX), under the conditions of three different buried depths, and soil moistures. Tentative detection probability for arid soil is found to be in excess of 80%.

Neutron Production Characteristics and Emission Properties of Spherically Convergent Beam Fusion

Abstract Experimental results of spherical glow discharge for a portable neutron source are presented. An experimental device consisting of a 45-cm-diam, 31-cm-high stainless steel cylindrical chamber was constructed in which a spherical mesh-type 30-cm-diam anode was installed. A spherical grid cathode made of 1.2-mm-diam stainless steel wire was made into a 7-cm-diam open spherical grid. The system was maintained at a constant pressure of 1 to 15 mTorr by feeding hydrogen or deuterium gas. The visible and ultraviolet emissions from the device were measured using the spectroscopic method. Strong emission lines of hydrogen were observed, and all hydrogen lines were broadened, remarkably, by Doppler and/or Stark effects. From these data, beam ion velocity, electron density and temperature of the core plasma were estimated. Using deuterium gas, a steady-state neutron production rate of 104 s−1 was observed at a discharge of 40 kV, 2 mA. In the low-current region of several milliamperes, the neutron production rate was proportional to the discharge current to the power from ~1.1 to 1.4. The beam-background reactions were dominant in the measured range of voltage and current.

Effects of Cusp Magnetic Field in Cylindrical Radially Convergent Beam Fusion Device

Abstract In order to evaluate the effect of cusp magnetic field in the cylindrical Radially Convergent Beam Fusion (RCBF) device, four kinds of experimental setups were examined. The maximum Neutron Production Rate (NPR) of 7.4 x 109 n/s was obtained at −80 kV and 15 A. As a result of the theoretical evaluation of fusion regimes in the RCBF device, the NPR normalized by the cathode current and the gas pressure was compared between the setups. The experimental data showed that the normalized NPR is highly correlated with the gas pressure, and it was independent of the setups. As the gas pressure decreased, the normalized NPR was increased. Hence, the present study suggests that the effect of the cusp magnetic field is to achieve lower pressure operation which improves the normalized NPR. The numerical estimation became in agreement with the experimental result by introducing an adjusting factor which was highly correlated with the pressure. The difference of the pressure is expected to affect some factors, such as an effective cathode transparency.

Research and Development of Landmine Detection System by a Compact Fusion Neutron Source

Abstract Current results are described on the research and development of an advanced anti-personnel landmine detection system by using a compact discharge-type fusion neutron source called IECF (Inertial-Electrostatic Confinement Fusion). Landmines are to be identified through backscattering of neutrons, and specific-energy capture γ-rays by hydrogen and nitrogen atoms in the landmine explosives. For this purpose, improvements in the IECF were made by various methods to achieve a drastic enhancement of neutron yields of more than 108 n/s in pulsed operation. This required R&D on the power source, as well as analysis of envisaged detection systems with multi-sensors. The results suggest promising and practical features for humanitarian landmine detection, particularly, in Afghanistan.

Research and Development on Humanitarian Landmine Detection System by Use of a Compact D-D Fusion Neutron Source

Abstract Current results are described on the research and development of the advanced humanitarian landmine detection system by using a compact discharge-type fusion neutron source called IECF (Inertial-Electrostatic Confinement fusion) devices. With a 50 mm-thick water-jacketed IEC device (IEC20C) of 200 mm inner diameter can have produced 107 neutrons/s stably in CW mode for 80 kV and 80 mA. Ample 10.8 MeV σ-rays produced through (n,σ) reaction with nitrogen atoms in the melamine (C3H6N6) powder (explosive simulant) are clearly measured by a BGO-NaI-combined scintillation sensor with distinct difference in case of with/without melamine, indicating identification of the buried landmines feasible.

Directional Detection of Nitrogen and Hydrogen in Explosives by Use of a DD-Fusion-Driven Thermal Neutron Source

Results of 5-year task are described on the research and development of the advanced explosive detection system by using a compact discharge-type fusion neutron source called Inertial-Electrostatic Confinement fusion (IECF) device and directional γ-ray detectors made of BGO and NaI. With >107 neutrons/s stably produced in CW operation, 10.8 and 2.22 MeV γ-rays from neutron-capture reactions with nitrogen and hydrogen atoms in explosives (TNT, RDX) are detected well, showing promising features for bulk explosive detections.

Research and development of the humanitarian landmine detection system by a compact fusion neutron source

A 5 year task is described on the research and development of the advanced humanitarian landmine detection system by using a compact discharge-type fusion neutron source called IECF (Inertial-Electrostatic Confinement fusion) device and 3 dual sensors made of BGO and NaI. With 107 D-D neutrons/s stably produced in steady-state mode, H-2.2 MeV, N-5.3, 10.8 MeV, gamma rays from (n, gamma) reaction with nitrogen atoms in the explosives are measured for two kinds of explosives (TNT, RDX), under the conditions of three different buried depths, and soil moistures. Final detection probabilities for arid soil are found to be 100 % in the present tests, i.e., depths not exceeding 15 cm, moisture content of 18.5 % or less, and 20-minute measurements. The neutron backscattering method is found also excellent.

Development of a High-performance Landmine Detection System Through Gamma-ray Detection by Using a Compact Fusion Neutron Source and Dual-sensors

An anti-personnel landmine detection system using an inertial-electrostatic confinement fusion (IECF) neutron source and dual sensors showed excellent performance, particularly, for humanitarian landmine detection. Averaged probability of detection (POD) in this test was found to be 100% for arid soil, and 99% for other conditions including very wet soil moisture of 18.5wt%. Further improvements in reliability by making use of neutron backscattering are found to be efficient.

Fundamental study of proton source based on inertial electrostatic confinement fusion for medical positron emission tomography

Summary form only given. The inertial electrostatic confinement (IEC) fusion has been mainly studied for application to a neutron source. However, it also has a potential applicable to a proton source. The IEC fusion system as a proton source has some advantages of low cost, portableness and easy handling compared with an accelerator such as a cyclotron. In this study, an IEC device was designed and tested for a proton source in order to produce a short-life radioisotope used for a medical positron emission tomography (PET). The device is made of 393-mm diameter, 342-mm high stainless steel cylindrical chamber, in which an open cylindrical grid anode of 200-mm diameter and an open cylindrical grid cathode of 40-mm diameter are set on the axis. In addition, a bucket-type ion source, which consists of sixteen ferrite magnets and sixteen filaments, is integrated with the chamber. A high voltage power supply of 100 kV, 100 mA for dc operation and 10 A for pulsed operation was also designed and used for the IEC device. By using this system, basic discharge characteristics, such as breakdown voltage versus pressure, operating voltage versus discharge current, etc. with changing gas pressure, were measured for hydrogen discharge. Then proton production rate was measured for deuterium discharge with changing operating voltage and discharge current.