CHARACTERIZATION AND COMPARSION OF NEUTRON GENERATORS OF IEC AND LINEAR D-T BY THE SPECTROMETRIC SYSTEM NGA-01

At a Glance

Metadata	Details
Publication Date	2021-01-01
Journal	EPJ Web of Conferences
Authors	Zdeněk Matěj, Michal Košťál, Evžen Novák, P. Alexa, Radim Uhlář
Institutions	VSB - Technical University of Ostrava, University of Defence
Citations	2
Analysis	Full AI Review Included

Executive Summary

This technical analysis focuses on the critical role of Chemical Vapor Deposition (CVD) diamond in high-energy neutron spectroscopy, as demonstrated by the characterization of D-T fusion generators.

Application Validation: The research successfully characterized complex neutron fields (1-16 MeV) generated by both linear (MP320) and cylindrical Inertial Electrostatic Confinement (IEC) D-T generators.
Diamond Detector Confirmation: Results obtained using the primary stilbene scintillator system (NGA-01) were independently verified and confirmed using a diamond detector, validating diamond’s superior performance in high-flux environments.
High-Flux Capability: The generators operate at high yields, reaching up to 5 x 10⁹ neutrons/s (stable operation) and maximum design parameters of 10¹⁰ neutrons/s, requiring the extreme radiation hardness of SCD.
Complex Spectra Resolution: The diamond detector successfully resolved complex spectral features, including the angular-dependent energy shift in the linear generator and the distinct two-peak structure observed in the IEC generator’s D-T reaction spectrum.
6CCVD Value Proposition: 6CCVD specializes in providing the high-purity Single Crystal Diamond (SCD) substrates, custom thicknesses (0.1 µm - 500 µm), and necessary metalization required for replicating and advancing these solid-state neutron detection systems.

Technical Specifications

The following hard data points were extracted from the characterization of the D-T neutron generators and associated detection systems:

Parameter	Value	Unit	Context
Neutron Energy Range (DT Fusion)	13 - 16	MeV	Depending on direction and deuteron energy
Measured Neutron Energy Range	1 - 15	MeV	Range measured by NGA-01 system
Linear Generator (MP320) Yield	10⁸	neutrons/s	Continuous regime (80 kV, 60 µA)
IEC Generator (NSD-350) Operating Yield	5 x 10⁹	neutrons/s	Stable operation (80 kV, 100 mA, 8 kW)
IEC Generator Maximum Yield	10¹⁰	neutrons/s	Maximum design parameters (160 kV, 150 mA, 24 kW)
Linear Generator Accelerating Voltage	80	kV	Experimental continuous regime
IEC Generator Accelerating Voltage	Max 160	kV	Maximum design parameter
Stilbene Detector Dimensions	45 x 45	mm	Cylindrical scintillator
D-T Reaction Yield Ratio (vs D-D)	65	Times Higher	NSD-350 generator comparison
D-T Neutron Peak Width (Angular Dependent)	< 0.4	MeV	Maximum width for MP320 generator
Getter Heating Temperature (IEC)	~540	°C	For D⁺ and T⁺ ion release

Key Methodologies

The characterization of the neutron fields relied on precise operation of the generators and advanced spectroscopic techniques, confirmed by solid-state diamond detectors.

Neutron Source Operation: Two D-T fusion generators were used: a linear generator (MP320) and a cylindrical Inertial Electrostatic Confinement (IEC) generator (NSD-350-24-DT-C-W-S).
Operating Regime: Experiments were performed primarily in the continuous regime, accelerating deuterons and/or tritons towards a metallic target (Linear) or confined plasma (IEC) at 80 kV.
Primary Detection System: The Neutron-Gamma Spectrometer NGA-01 was employed, utilizing a stilbene scintillation detector coupled with an active voltage divider (MOS-FET based) to achieve excellent linearity at high pulse rates (> 10⁵ counts/s) and filter out gamma radiation.
Data Acquisition: Signals were digitized at 500 MHz with 12 bits resolution, processed using advanced integration method algorithms in an FPGA.
Confirmatory Detection: Results, including the angular shift of the neutron peak and the complex two-peak structure of the IEC generator, were verified by independent measurement using a diamond detector.
Spectrum Calculation: Acquired recoiled proton spectra were subjected to deconvolution using Maximum Likelihood Estimation to calculate the final neutron spectral density.
Simulation Verification: Experimental data was compared against theoretical predictions generated using MCNP6 simulations, accounting for generator geometry and internal interactions.

6CCVD Solutions & Capabilities

The successful use of diamond detectors in this high-energy, high-flux environment underscores the necessity of high-quality CVD diamond materials. 6CCVD is uniquely positioned to supply the materials and customization required for replicating or extending this research into next-generation neutron spectroscopy.

Research Requirement	6CCVD Solution & Capability	Technical Advantage & Sales Driver
Applicable Materials	Optical Grade Single Crystal Diamond (SCD)	SCD is essential for high-resolution spectroscopy and superior charge collection efficiency, crucial for resolving the complex, multi-peak spectra observed in the IEC generator (Fig. 8).
Detector Thickness Optimization	SCD Thickness Control (0.1 µm - 500 µm)	We provide precise thickness control, allowing researchers to optimize detector efficiency and sensitivity for specific neutron energy ranges (e.g., thin layers for recoil proton detection in the 1-15 MeV range).
High Voltage Operation	High-Purity SCD Substrates	Our SCD material exhibits extremely low defect density, ensuring high breakdown voltage and stable operation necessary for detectors operating in high-field environments (up to 160 kV acceleration voltage).
Custom Detector Geometry	Custom Dimensions and Laser Cutting	While the paper used standard detectors, 6CCVD offers custom plates up to 125 mm (PCD) and precise laser cutting for unique geometries required for angular dependence studies or integration into complex shielding assemblies.
Electrical Contacting	In-House Custom Metalization Services	We offer internal metalization capabilities (Au, Pt, Pd, Ti, W, Cu) to create reliable ohmic or Schottky contacts, which are critical for the stable performance of solid-state diamond detectors in high-radiation environments.
Engineering Support	Specialized PhD Team Consultation	6CCVD’s in-house PhD team can assist with material selection, surface preparation (Ra < 1nm), and metal stack design for similar High-Energy Neutron Spectroscopy and mixed n/γ field detection projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. Global shipping (DDU default, DDP available) ensures timely delivery for international research projects.

View Original Abstract

This article focuses on description of two different neutron fields from linear and cylindrical Inertial Electrostatic Confinement (IEC) neutron generators. Both of these generators are well defined and commonly used. They use a deuterium-tritium reaction that produces neutrons with energies in the range 13 - 16 MeV, depending on the direction and the energy of the incoming deuterium nucleus. Two-parametric spectrometric system for neutron/gamma mixed fields NGA-01 was used to characterize neutron spectra in the proximity of generators. The cylindrical 45x45 mm stilbene scintillator was connected to this device using an active voltage divider. This way, we were able to measure neutron energies in the range 1 - 15 MeV while filtering out gamma radiation, even when counts per second is high. For the neutron spectrum calculation recoil spectra using deconvolution through maximum likelihood estimation was used. Measured neutron spectra have been compared with simulations realized via MCNP6. According to the theoretical prediction, these two types of generators produce different neutron fields. In case of the linear generator the target is very close to point located tritium bombarded by deuterons. Thus the neutron spectrum varies depending on the angle between the detector axis and the axis of the generator. Both experimental results and simulation show a shift of the neutron energy peak in pulse height histogram. For IEC type generators the neutron spectrum is more complicated. The shape and the position of the neutron energy peak depend heavily on the position of the detector. The most prominent effect is in the position in the plane perpendicular to the generator axis. In this case, the peak splits into two peaks that can be measured and distinguished. These results were verified by the diamond detector which was also used for characterization of the IEC type generator.

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Original Source

DOI: https://doi.org/10.1051/epjconf/202124718004