DOW-UAP-D125, AAWSAP DIRD, Inertial Electrostatic Confinement Fusion, March 2010

This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys inertial electrostatic confinement (IEC) fusion, a relatively unconventional fusion concept that uses electric fields rather than the more established magnetic or laser-based approaches to confine ions, and it reviews both the underlying physics and the experimental work associated with the concept. The report emphasizes that IEC may have nearer-term value as a compact neutron, proton, or x-ray source and as a platform for studying experimental fusion approaches, while also presenting more ambitious possibilities such as aneutronic power generation and propulsion applications. At the same time, it makes clear that the concept remained far from practical fusion power, with experimental devices operating several orders of magnitude below breakeven and with major unresolved issues involving confinement, losses, grid damage, and scale-up. Overall, the document treats IEC as a technically interesting but still highly speculative path toward fusion energy, while suggesting that its more limited spin-off applications were more plausible in the near term than its long-range power generation or propulsion applications.

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Defense
Intelligence
Reference
Document
Acquisition Threat Support
10 March 2010
ICOD: 1 December 2009
DIA-08-1003-006
Inertial Electrostatic
Confinement Fusion
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Inertial Electrostatic Confinement Fusion
Prepared by:
Acquisition Support Division (DW0-3)
Defense Warning Office
Directorate for Analysis
Defense Intelligence Agency
Author:
AAP Person 70
Administrative Note
COPYRIGHT WARNING: Further dissemination of the photographs in this publication is not authorized.
This product is one in a series of advanced technology reports produced in FY 2009
under the Defense Intelligence Agency, Defense Warning Office's Advanced Aerospace
Weapon System Applications (AAWSA) Program. Comments or questions pertaining to
I
this document should be addressed to!AAP Person 1 AAWSA Program
Manager, Defense Intelligence Agency, ATTN: CLAR/DWO-3, Bldg 6000, Washington,
DC 20340-5100.
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Contents
Preface.................................................................................................................vii
Section I. IEC Background and Basics .................................................................... 1
IEC Background.......................................................................................,.,1••········· 3
IEC Basics ........................................................................................................... 5
Bussard HEPS (or Polywell) Concept............................................................ 10
Barnes Nebel Penning Trap .......................................................................... 10
Nebel POPS Device ..............................................................................,......... 10
Miley's "Ion Injected" Device....................................................................... 11
Closing Remarks ......................................................................................11,,,•••••• 12
References ...................................................................................................... 13
Section II. Select Experiments ............................................................................. 14
Closing Comments............................................................................................ 20
References ...................................................................................................... 20
Section III. Other Geometries.............................................................................. 21
Cylindrical IECs ............................................................................................... 21
Electrically-Driven IEC Jet Thruster................................................................... 22
Relation to Other Prior Thrusters ................................................................. 23
JET Extraction From a Spherical IEC............................................................. 24
Description of the IEC Jet Thruster ............................................................. 24
Comparison to a Conventional "Plasma" Thruster ........................................ 24
Jet Extraction ............................................................................................... 26
Experimental Jet Design and Performance ................................................... 26
Scale-up to p-11B IEC Space Power Unit/Thruster........................................ 28
The Dipole Assisted IEC (DaIEC) .................................................................. 29
DAIEC Experiments .......................................................................................... 30
Khachan's Studies at U of Sydney .................................................................... 31
Concluding Remarks......................................................................................... 32
References ............................................................................................... 32
11 •••••••••
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Section IV. IEC Theory ......................................................................................... 34
Potential Well Structure ................................................................................... 38
Tzonev et al. - Deep Well Study ....................................................................... 39
Momota et al. - Study of Virtual Electrode Strudure........................................ 41
Kim - Stability Analysis.................................................................................... 41
Rider - Energy Balance Study .......................................................................... 43
Neutron Source Simulations............................................................................... 44
References ....................................................................................................... 46
Section V. Potential Applications.......................................................................... 46
Neutron/proton/Xray Sources ............................................................... ......... 46
Integrated X-Ray/Neutron Sources ................................................................ 47
Nuclear and Chemical Explosive Detection Techniques ................................ 47
Overview for Weapons/Nuclear Material Simulation Articles ....................... 48
Pulsed Power for the Inspection Station ...................................................... 49
Design of the Total Integrated Interrogation System................................... 50
Detector Array and Analysis System ............................................................ 52
Space Propulsion.............................................................................................. 54
Magnetically-Channeled Spherical IEC Array (MCSA) Concept ......................... 56
Recirculation of Radial Belt Cone Losses ..................................................... 57
Retrapping of Axial-Loss Particles................................................................ 58
Concluding Remarks........................................................................................... 59
References ........................................................................................................ 59
Section VI. Possible Next Step Breakeven Experiment ......................................... 60
Demonstration of Net Energy Gain using IEC Aneutronic Fusion ...................... 60
Vision of a Future p-118 Fusion Plant.......................................................,......... 61
Proposed Breakeven Experiment...................................................................... 62
Concluding Remarks......................................................................................... 64
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Figures
Figure 1.1. An UIUC Spherical IEC.............................................................................. 1
Figure 1.2. Idealized Potential Structure Calculated by Hirsch for Monoenergetic
Ions With No Angular Momentum......................................................... 6
Figure 1.3. Discharge Modes in Gridded Devices Identified by Miley ...................... 9
Figure 1.4. Photo of Star Mode Seen Through a Reaction Vessel Port Window ....... 9
Figure 1.5. Schematic of the UIUC RF Gun Injector for IEC Experiments.............. 11
Figure 1.6. RF Gun Attached to an IEC Chamber in the UIUC Laboratory.............. 12
Figure 1.7. Photo of Center Spot Formation ......................................................... 12
Figure 2.1. The "Historic" Early IEC Ion Injection Experiment ............................. 14
Figure 2.2. Neutron Rates Measured With the IEC: Neutron Rates Measured With
the IEC of Figure 2.1 Exceeded 109 DT n/s at 150 kV ......................... 14
Figure 2.3. Photograph of a STAR Mode Discharge ............................................... 16
Figure 2.4. IEC Landmine Detection Project at Kyoto University .......................... 17
Figure 2.5. Scheme for Landmine Detection Using a Hybrid Magnetron Type
IEC Neutron Source ............................................................................ 18
Figure 2.6. 3He Ion Source for Use in 3He -3He Fusion Rate Studies at the U Of
Wisconsin ............................................................................................ 19
Figure 3.1. Two Types of Cylindrical IECs............................................................. 22
Figure 3.2. Jet Operational Mode in Experimental IEC Device and Jet Set-Up ...... 24
Figure 3.3. Illustration of the IEC Jet Thruster Experiment Showing Central
Grid and Two Jet Grids ....................................................................... 27
Figure 3.4. Dipole Reactor Propulsion Scheme ..................................................... 29
Figure 3.5. Dipole Magnetic Field and Layout of Devices ...................................... 30
Figure 3.6. Electron Density Vs. Dipole Magnet Field Strength at 25mtorr, 20mA 31
Figure 4.1. Cross Section of the Experimental Layout of the PFX-I Experiment.... 34
Figure 4.2. Detail of the Anode and the Ion Injection Port in PFX-I ..................... 35
Figure 4.3. Plot of the Q-Value ............................................................................. 37
Figure 4.4. Sketch of Two Opposite Limits of the Beam-Maxwellian Equilibrium .. 38
Figure 4.5. The Definition of the Double Well Depth ............................................. 39
Figure 4.6. The Definition of the Parallel and Perpendicular Velocities at the IEC
Cathode Grid ...................................................................................... 39
Figure 4.7. The Double Well Potential Calculated With IXL Code ......................... 40
Figure 4.8. Ion Density Profile for Potential Well ................................................. 40
Figure 4.9. The D-D Fusion Reaction Rate Versus Cathode Current ..................... 40
Figure 4.10. Plot of Growth Rate of Spherically Converging/Diverging Ion-Beam
Instability......................................................................................... 42
Figure 4.11. Diagram Showing Equipotential Surfaces of the IEC Cathode Grid .. 45
Figure 4.12. Results for Calculations for Ion Energy Distributions 1st Pass ......... 45
Figure 5.1. Block Diagram of the IEC Pulsed Power System ................................. 49
Figure 5.2. Schematic (View From Top) of a Broad Coverage IEC Inspection
··············································••11••·······
System for Luggage Inspection 51
Figure 5.3. Further Illustration of the Integrated System for Airport Luggage
Inspection ........................................................................................... 53
Figure 5.4. Further Illustration of the Integrated .System for Ship Container
Inspection .......................................................................................... 53
Figure S.S. Image of a Fusion II Spaceship, a 750-MWe IEC Fusion-Powered
Manned Spacecraft With Ion Thruster Propulsion ............................. 54
Figure 5.6. Scale Schematic of Fusion Ship II, a 750-MWe IEC Fusion
Spacecraft .......................................................................................... 55
Figure 5.7. Illustration of a Three-Unit MCSA Device............................................ 57
Figure 5.8. Diagram of Belt-Cusp Fields and Particle Recirculation ....................... 57
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Figure 5.9. Axial Magnetic Field Strength Along Two-Unit MCSA Centerline ......... 58
Figure 5.10. Diagram of Direction Randomization (KAM Effect) Due to the
Magnetic Field Null Region in the IEC ............................................... 59
Figure 6.1. p-11B Fusion Cross Section Energy Requirements............................... 62
Figure 6.2. IEC System With Radio Frequency Ion Gun ....................................... 63
Figure 6.3. Multiple Ion Gun Concept ................................................................... 63
Figure 6.4. Differentially Pumped RF-Driven Ion Gun........................................... 63
Tables
Table 3.1. Estimated Performance Parameters or the IEC Ion Thruster ............... 28
Table 4.1. Comparison of Analytical and Numerical Estimates of Q-Values in a
Beam-Dominated Solution -- for a SO-kV Square Well ......................... 32
Table 5.1. Three Kinds of Techniques Previously Used in Explosives Detection
System................................................................................................. 48
Table 5.2. Comparison of IEC Design and Magnetic Fusion Design ....................... 56
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Inertial Electrostatic Confinement Fusion
Preface
This report is intended to provide the reader with an overview of the basics,
current experimental status, supporting theory, and potential applications of
inertial electrostatic confinement (IEC} fusion. Emphasis is placed on work in
these areas at the University of Illinois Urbana-Champaign, although some
other research is brought in.
The report shows that IEC is a unique approach to fusion in that it offers a
number of "spin-off" applications, such as a small neutron source for neutron
activation analysis on the route to fusion power. The report further shows that
IEC is one of the few potential fusion approaches that can potentially burn
aneutronic fuels like p-11B (hydrogen - Boron 11). In aneutronic fusion,
neutrons carry no more than 1% of the total released energy, greatly reducing
problems associated with neutron radiation. That ability, combined with its
simple mechanical structure and small size, make the IEC reactor, if achieved,
an ideal fusion power unit. Present experimental devices are four to five
orders of magnitude below breakeven (energy out/in = 1) energy gain for p-
11B. However, it is argued that the ability to study the physics in very-small­
volume plasmas makes it possible to rapidly investigate scale-up to a power­
producing device. As an example, the report concludes with a conceptual
experiment proposed for demonstration of breakeven conditions for p-11B
using a hydrogen plasma simulation.
The author has purposely tried to avoid use of ,equations in this report to
enhance readability and to stress concepts rather than analysis. However,
considerable analysis is provided in a number of the source references cited.
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Section I . IEC Background and Basics
Before considering detail, it is helpful to obtain a rough idea of how inertial electrostatic
conf