Increasing the High Voltage Capabilities and Exploring Parameter Space of an Inertial Electrostatic Confinement Fusion Neutron Source for the Detection of Chemical Explosives PDF Download
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Author: Matthew K. Michalak Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The objectives of the work presented here include understanding key operating principles and providing precise data sets that can be used to test inertial electrostatic confinement (IEC) fusion theory and optimize IEC device operation. The underlying physical behavior was separated from superficial trends observed in an IEC device at the University of Wisconsin--Madison (UW). The effects of changing voltage (30-170 kV) and current (30-100 mA) were thoroughly explored, pressure effects (0.15-1.25 mTorr) were mapped, and the effect of impurities in the system was quantified. The most challenging part of this work was designing a high voltage feedthrough that could reliably operate at higher voltages for far longer times than previously attained. A system to detect conventional explosives using fusion neutrons was also designed, constructed, and tested. Precise data sets were created by taking into account and minimizing the effects of short and long term trends in the experiment. Detailed meter current scans were taken that showed a linear relationship of the neutron production rate with current. Cathode voltage scans were slightly greater than linear in the neutron rate from 30 to 170 kV, but the rate increase diminished to near linear as 170 kV was approached. A new high voltage feedthrough was designed that surpassed the performance of past UW IEC lab feedthroughs and shows promise for long duration operation at still higher voltages. Limitations of other equipment in the IEC lab prevented testing the feedthrough to voltages above 175 kV. A more robust construction of the feedthrough and reducing the consequences of a feedthrough failure were also important design criteria that were met. A detector array was made to detect explosives via the 10.8 MeV neutron capture prompt gamma from nitrogen. Signals from four separate detectors were combined to make the individual detectors act similar to one large detector. The detector signals were both summed and combined to compare the performance of the two methods. An overwhelming background radiation signal and insufficient time resolution were two factors that led to the combined signal not performing as well as the summed signal.
Author: Matthew K. Michalak Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The objectives of the work presented here include understanding key operating principles and providing precise data sets that can be used to test inertial electrostatic confinement (IEC) fusion theory and optimize IEC device operation. The underlying physical behavior was separated from superficial trends observed in an IEC device at the University of Wisconsin--Madison (UW). The effects of changing voltage (30-170 kV) and current (30-100 mA) were thoroughly explored, pressure effects (0.15-1.25 mTorr) were mapped, and the effect of impurities in the system was quantified. The most challenging part of this work was designing a high voltage feedthrough that could reliably operate at higher voltages for far longer times than previously attained. A system to detect conventional explosives using fusion neutrons was also designed, constructed, and tested. Precise data sets were created by taking into account and minimizing the effects of short and long term trends in the experiment. Detailed meter current scans were taken that showed a linear relationship of the neutron production rate with current. Cathode voltage scans were slightly greater than linear in the neutron rate from 30 to 170 kV, but the rate increase diminished to near linear as 170 kV was approached. A new high voltage feedthrough was designed that surpassed the performance of past UW IEC lab feedthroughs and shows promise for long duration operation at still higher voltages. Limitations of other equipment in the IEC lab prevented testing the feedthrough to voltages above 175 kV. A more robust construction of the feedthrough and reducing the consequences of a feedthrough failure were also important design criteria that were met. A detector array was made to detect explosives via the 10.8 MeV neutron capture prompt gamma from nitrogen. Signals from four separate detectors were combined to make the individual detectors act similar to one large detector. The detector signals were both summed and combined to compare the performance of the two methods. An overwhelming background radiation signal and insufficient time resolution were two factors that led to the combined signal not performing as well as the summed signal.
Author: Aaron N. Fancher Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
This work details the advancement and understanding of fusion neutron generation capabilities using a deuterium fueled spherical gridded inertial electrostatic confinement (IEC) device operating up to 200 kV at the University of Wisconsin-Madison. The goal of this work was to extend the experimental and theoretical understanding of gridded IEC operations to previously unachieved 200 kV cathode operation and to investigate long term trends in the neutron production rate performance. To support this experimental investigation, hardware with the capability to reliably sustain 200 kV operation was successfully developed by constructing a resistively divided 2-stage high voltage vacuum feedthrough. Repeated measurements of the neutron production rate under fixed experimental conditions were performed over the span of 100 operational runs, which showed an upward trend in the neutron production rate performance. An investigation into the impact of impurity gas in the chamber during operation showed the reduction of impurity gas in the system and an increase in neutron production rate are correlated. An estimation of the neutron production rate increase over these runs due to embedded fusion reactions in the chamber wall showed a fuel density build up near the surface by the implantation of fast neutral deuterium particles leaving the system can plausibly account for the upward trend in neutron production rate measurements. Parametric studies measured the neutron production rate with variations in the device cathode voltage (10-200 kV), cathode current (30-100 mA) and chamber pressure (0.2-1.7 mTorr D2), and comparisons with a theoretical model are made. The results of this study showed the neutron production rate scales linearly with current as expected with a beam-target fusion regime and scales in a complex manner with voltage and pressure. Comparisons made to a theoretical model of the neutron production rate using an integral transport code showed the absolute neutron production rate prediction by the model is a factor of 7.8 lower than experimental measurements. A new record for steady-state D-D neutron production rate of 3.8x108 neutrons/s has been achieved in a gridded IEC device at a cathode voltage of 200 kV, cathode current of 100 mA, and chamber pressure of 1.0 mTorr D2.
Author: Publisher: ISBN: Category : Languages : en Pages : 4
Book Description
Inertial Electrostatic Confinement (IEC) is one of the earliest plasma confinement concepts, having first been suggested by P.T. Farnsworth in the 1950s. The concept involves a simple apparatus of concentric spherical electrostatic grids or a combination of grids and magnetic fields. An electrostatic structure is formed from the confluence of electron or ion beams. Gridded IEC systems have demonstrated neutron yields as high as 2*10 [10]. neutrons/sec in steady state. These systems have considerable potential as small, inexpensive, portable neutron sources for assaying applications. Neutron tomography is also a potential application. This paper discusses the IEC concept and how it can be adapted to a steady-state assaying source and an intense pulsed neutron source. Theoretical modeling and experimental results are presented.
Author: International Atomic Energy Agency Publisher: IAEA Radiation Technology Repo ISBN: 9789201251107 Category : Science Languages : en Pages : 145
Book Description
This publication addresses recent developments in neutron generator (NG) technology. It presents information on compact instruments with high neutron yield to be used for neutron activation analysis (NAA) and prompt gamma neutron activation analysis in combination with high count rate spectrometers. Traditional NGs have been shown to be effective for applications including borehole logging, homeland security, nuclear medicine and the on-line analysis of aluminium, coal and cement. Pulsed fast thermal neutron analysis, as well as tagged and timed neutron analysis, are additional techniques which can be applied using NG. Furthermore, NG can effectively be used for elemental analysis and is also effective for analysis of hidden materials by neutron radiography. Useful guidelines for developing NG based research laboratories are also provided in this publication.
Author: Publisher: ISBN: Category : Languages : en Pages : 3
Book Description
The objective of this research project, development of a unique portable inertial electrostatic confinement (IEC) neutron source (106 2.5-MeV neutrons/second-level) has been achieved. A majority of the experimental work required for the project was reported in the 1993 Annual Report. (The abstract and table of contents for that report arc included here as Appendix A for convenience. Full copies can be obtained upon request to the PI.) Unfortunately, the DOE program providing support for the project was canceled and funding was not available to continue the project in 199495. However, to provide time to explore some innovative potential applications for upgraded versions of the IEC, a no-cost extension of the contract was requested and granted in 1994. This follow-on work, mostly involving conceptual design studies, is reported here.
Author: Publisher: ISBN: Category : Languages : en Pages : 5
Book Description
We are addressing the need to measure nuclear wastes, residues, and spent fuel in order to process these for final disposition. For example, TRU wastes destined for the WIPP must satisfy extensive characterization criteria outlined in the Waste Acceptance Criteria, the Quality Assurance Program Plan, and the Performance Demonstration Plan. Similar requirements exist for spent fuel and residues. At present, no nondestructive assay (NDA) instrumentation is capable of satisfying all of the PDP test cycles (particularly for Remote-Handled TRU waste). One of the primary methods for waste assay is by active neutron interrogation. The objective of this project is to improve the capability of all active neutron systems by providing a higher intensity neutron source (by about a factor of 1,000) for essentially the same cost, power, and space requirements as existing systems. This high intensity neutron source is an electrostatically confined (IEC) plasma device. The IEC is a symmetric sphere that was originally developed in the 1960s as a possible fusion reactor. It operates as DT neutron generator. Although it is not likely that this device will scale to fusion reactor levels, previous experiments1 have demonstrated a neutron yield of 2 x 1010 neutrons/second on a table-top device that can be powered from ordinary laboratory circuits (9 kilowatts). Subsequently, the IEC physics has been extensively studied at the University of Illinois and other locations. We have established theoretically the basis for scaling the output up to 1 x 1011 neutrons/second. In addition, IEC devices have run for cumulative times approaching 10,000 hours, which is essential for practical application to NDA. They have been operated in pulsed and continuous mode. The essential features of the IEC plasma neutron source, compared to existing sources of the same cost, size and power consumption, are: Table 1: Present and Target Operating Parameters for Small Neutron Generators Parameter Present IEC Target or Already Proven Neutron Yield (n/s) 108 1011 Lifetime (hours) 500 10,000 Operation Pulsed Pulsed or steady state Nominal cost $k $100k Same Power 1kW 25kW 5. Methods and Results: The design of a conventional IEC source is deceptively simple. The basic system is a spherical vacuum chamber containing a spherical grid. The grid is raised to a high negative potential. A breakdown develops between the chamber wall and the grid, and this plasma becomes a source of positive deuterium and tritium ions. These ions are accelerated to the center of the vacuum chamber sphere where they may collide. The ion energy may achieve the full potential of the accelerating grid. If the grid is raised to a nominal 100 kV, the D-T fusion cross section becomes large and the neutron production proceeds. The IEC concept was initially developed in the 1950s and 1960s by R.L. Hirsch and collaborators. It was originally proposed as a possible plasma fusion energy device. The idea was initially presented to the DOE with a table-top experiment using ordinary office power. That system produced in excess of 106 neutrons per second. Although the IEC was not favored for a future electric energy generator, the application as a potential neutron source was clearly established. Using nominal laboratory power and a modest sized sphere, Hirsch was able to achieve a maximum neutron yield of 2xl010 neutrons per second (in D-T)in the mid 1960s.
Author: Publisher: ISBN: Category : Languages : en Pages : 4
Book Description
This paper concerns the development of a neutron so based on the inertial electrostatic confinement (IEC) of a low density fusion plasma in a gridded, spherically-focusing device. With the motivation of using such sources for nondestructive evaluation (NDE) applications, the focus of the development is on : Small size devices, sealed operation with D2 or D2/T2 mixtures, Power-utilization and neutron-output optimization, and integration into an assay system. In this paper, we describe an experimental system that has been established for the development and testing of IEC neutron sources, and we present preliminary results of tests conducted for 25-cm and 15-cm diameter IEC devices.
Author: National Research Council Publisher: National Academies Press ISBN: 030908637X Category : Science Languages : en Pages : 177
Book Description
Recent scientific and technical advances have made it possible to create matter in the laboratory under conditions relevant to astrophysical systems such as supernovae and black holes. These advances will also benefit inertial confinement fusion research and the nation's nuclear weapon's program. The report describes the major research facilities on which such high energy density conditions can be achieved and lists a number of key scientific questions about high energy density physics that can be addressed by this research. Several recommendations are presented that would facilitate the development of a comprehensive strategy for realizing these research opportunities.
Author: Thomas J. Dolan Publisher: Springer Science & Business Media ISBN: 1447155564 Category : Technology & Engineering Languages : en Pages : 816
Book Description
Magnetic Fusion Technology describes the technologies that are required for successful development of nuclear fusion power plants using strong magnetic fields. These technologies include: • magnet systems, • plasma heating systems, • control systems, • energy conversion systems, • advanced materials development, • vacuum systems, • cryogenic systems, • plasma diagnostics, • safety systems, and • power plant design studies. Magnetic Fusion Technology will be useful to students and to specialists working in energy research.
Author: Matthew K. Michalak
Author: Matthew K. Michalak
Author: Aaron N. Fancher
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Author: International Atomic Energy Agency
Author: Blair Patrick Bromley
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Author: 
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Author: National Research Council
Author: Thomas J. Dolan