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Plasma power station with quasi spherical direct drive capsule for fusion yield and inverse diode for driver-target coupling

Fusion Science and Technology

VanDevender, J.P.; Cuneo, M.E.; Slutz, S.A.; Herrmann, Mark H.; Vesey, Roger A.; Sinars, Daniel S.; Seidel, David B.; Schneider, Larry X.; Mikkelson, Kenneth A.; Harper-Slaboszewicz, V.H.; Peyton, B.P.; Sefkow, Adam B.; Matzen, M.K.

The Meier-Moir economic model for Pulsed Power Driven Inertial Fusion Energy shows at least two approaches for fusion energy at 7 to 8 cents/kw-hr: One with large yield at 0.1 Hz and presented by M. E. Cuneo at ICENES 2011 and one with smaller yield at 3 Hz presented in this paper. Both use very efficient and low cost Linear Transformer Drivers (LTDs) for the pulsed power. We report the system configuration and end-toend simulation for the latter option, which is called the Plasma Power Station (PPS), and report the first results on the two, least mature, enabling technologies: a magnetically driven Quasi Spherical Direct Drive (QSDD) capsule for the fusion yield and an Inverse Diode for coupling the driver to the target. In addition, we describe the issues and propose to address the issues with a prototype of the PPS on the Saturn accelerator and with experiments on a short pulse modification of the Z accelerator test the validity of simulations showing megajoule thermonuclear yield with DT on a modified Z.

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Plasma Power Station with Quasi Spherical Direct Drive Capsule for Fusion Yield and Inverse Diode for Driver-Target Coupling

Fusion Science and Technology

Cuneo, M.E.; Matzen, M.K.; Sinars, Daniel S.; Slutz, Stephen A.; Herrmann, Mark H.; Vesey, Roger A.; Seidel, David B.; Schneider, Larry X.; Mikkelson, Kenneth A.; Harper-Slaboszewicz, V.H.; Sefkow, Adam B.

The Meier-Moir economic model for Pulsed Power Driven Inertial Fusion Energy shows at least two approaches for fusion energy at 7 to 8 cents/kw-hr: One with large yield at 0.1 Hz and presented by M. E. Cuneo at ICENES 2011 and one with smaller yield at 3 Hz presented in this paper. Both use very efficient and low cost Linear Transformer Drivers (LTDs) for the pulsed power. Here, we report the system configuration and end-to-end simulation for the latter option, which is called the Plasma Power Station (PPS), and report the first results on the two, least mature, enabling technologies: a magnetically driven Quasi Spherical Direct Drive (QSDD) capsule for the fusion yield and an Inverse Diode for coupling the driver to the target. In addition, we describe the issues and propose to address the issues with a prototype of the PPS on the Saturn accelerator and with experiments on a short pulse modification of the Z accelerator test the validity of simulations showing megajoule thermonuclear yield with DT on a modified Z.

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New self-magnetically insulated connection of multi-level accelerators to a common load

Digest of Technical Papers-IEEE International Pulsed Power Conference

VanDevender, J.P.; Langston, William L.; Pasik, Michael F.; Coats, Rebecca S.; Pointon, Timothy D.; Seidel, David B.; Jennings, C.A.; McKee, G.R.; Schneider, Larry X.

We have developed a new type of convolute called the Clam Shell MITL (CSMITL) to couple multi-level accelerators to a common load. The CSMITL has magnetic nulls only at large radius where the cathode electric field is kept below the threshold for emission, has only a simply connected magnetic topology to avoid plasma motion along magnetic field lines into highly stressed gaps, and has electron injectors that ensure efficient electron flow even in the limiting case of self-limited MITLs. We report the first experimental results on a CSMITL, which convolutes two disk feeds on the Saturn accelerator into a single disk feed. Experiments with a high impedance electron beam load operating at twice the self-limited impedance of the CSMITL confirm key design features and demonstrate robust operation. © 2011 IEEE.

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PIC simulations of power flow in a linear transformer driver for radiographic applications

Digest of Technical Papers-IEEE International Pulsed Power Conference

Pointon, Timothy D.; Seidel, David B.; Leckbee, Joshua L.; Oliver, Bryan V.

The 7 cavity, 1 MV linear transformer driver for radiography at Sandia National Laboratories has recently been upgraded to 21 cavities with an output voltage of 2.5 MV. In this paper, results from 2-D, r-z particle-in-cell simulations of the full 21 cavity system are presented. Each cavity feed is driven with its own external RLC circuit that is independently triggered, and has a realistic 45° slanted vacuum/insulator. Electrons are emitted from the central cathode with a conventional space-charge-limited emission model. Detailed diagnostics monitor electron loss to the anode, cavity conductors, and the insulators. The most significant and encouraging result is that the simulations have absolutely no electron loss to the insulators, even with large random variations in the trigger timing. © 2011 IEEE.

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Inverse diode for combination of multiple modules and fusion driver-target standoff

Digest of Technical Papers-IEEE International Pulsed Power Conference

VanDevender, J.P.; Seidel, David B.; Mikkelson, Kenneth A.; Thomas, Rayburn D.; Peyton, B.P.; Harper-Slaboszewicz, V.H.; McBride, Ryan D.; Cuneo, M.E.; Schneider, Larry X.

A newly invented, multi-megampere inverse diode converts the currents in many electron beams to current in a single Magnetically Insulated Transmission Line (MITL) for driving a common load. Electrons are injected through a transparent anode, cross a vacuum gap, and are absorbed in the cathode of the inverse diode. The cathode current returns to the anode through a load and generates electric and magnetic fields in the anode-cathode gap. Counter streaming electron flow is prevented by self-magnetic insulation in most of the inverse diode and by self-electrostatic insulation where the magnetic field is insufficient. Two-dimensional simulations with a 40 MA, 4 MeV, 40 ns electron beam at 3.5 kA/cm 2 current density, 5 degree beam divergence, and up to 60 degree injection angle show 85% of the injected electron beam current is captured and fed into the MITL. Exploratory experiments with a 2.5 MA, 2.8 MeV, 40 ns electron beam at 2 kA/cm 2at injection normal to the anode gave 70+/-10% collection efficiency in an unoptimized inverse diode. The inverse diode appears to have the potential of coupling multiple pulsed power modules into a common load at rates of change of current ∼1.6× 10 15 A/s required for a fusion energy device called the Plasma Power Station with a Quasi Spherical Direct Drive fusion target. © 2011 IEEE.

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Controlling feed electron flow in MITL-driven radiographic diodes

Digest of Technical Papers-IEEE International Pulsed Power Conference

Seidel, David B.; Pointon, Timothy D.; Oliver, Bryan V.

The electrons flowing in a coaxial magnetically insulated transmission line (MITL), if allowed to flow uncontrolled into a radiographic electron diode load, can have an adverse impact on the performance of the system. Total radiation dose, impedance lifetime, and spot quality (size, shape, position, and stability) can all be affected. Current approaches to deal with this problem require a large volume in the vicinity of the electron diode load. For applications where this volume is not available, an alternate method of controlling the feed electrons is needed. In this paper, we will investigate various ideas for dealing with this issue and present results showing the properties of the various schemes investigated. © 2011 IEEE.

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EMPHASIS/Nevada UTDEM user guide. Version 2.0

Turner, C.D.; Pasik, Michael F.; Seidel, David B.

The Unstructured Time-Domain ElectroMagnetics (UTDEM) portion of the EMPHASIS suite solves Maxwell's equations using finite-element techniques on unstructured meshes. This document provides user-specific information to facilitate the use of the code for applications of interest. UTDEM is a general-purpose code for solving Maxwell's equations on arbitrary, unstructured tetrahedral meshes. The geometries and the meshes thereof are limited only by the patience of the user in meshing and by the available computing resources for the solution. UTDEM solves Maxwell's equations using finite-element method (FEM) techniques on tetrahedral elements using vector, edge-conforming basis functions. EMPHASIS/Nevada Unstructured Time-Domain ElectroMagnetic Particle-In-Cell (UTDEM PIC) is a superset of the capabilities found in UTDEM. It adds the capability to simulate systems in which the effects of free charge are important and need to be treated in a self-consistent manner. This is done by integrating the equations of motion for macroparticles (a macroparticle is an object that represents a large number of real physical particles, all with the same position and momentum) being accelerated by the electromagnetic forces upon the particle (Lorentz force). The motion of these particles results in a current, which is a source for the fields in Maxwell's equations.

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Copy of An overview of pulse compression and power flow in the upgraded Z pulsed power driver

Savage, Mark E.; Maenchen, John E.; McDaniel, Dillon H.; Pasik, Michael F.; Pointon, Timothy D.; Owen, Albert C.; Seidel, David B.; Stoltzfus, Brian S.; Struve, Kenneth W.; Warne, Larry K.; Bennett, Lawrence F.; Woodworth, Joseph R.; Bliss, David E.; Clark, Waylon T.; Coats, Rebecca S.; Elizondo-Decanini, Juan M.; LeChien, Keith R.; Harjes, Henry C.; Lehr, J.M.

Abstract not provided.

Initial design and results from an ion current collection diagnostic for the triggered plasma opening switch experiment

Jackson, Daniel P.; Savage, Mark E.; Seidel, David B.

Study of the triggered plasma opening switch (TPOS) characteristics is in progress via an ion current collection diagnostic (ICCD), in addition to offline apparatus. This initial ion current collection diagnostic has been designed, fabricated, and tested on the TPOS in order to explore the opening profile of the main switch. The initial ion current collection device utilizes five collectors which are positioned perpendicularly to the main switch stage in order to collect radially traveling ions. It has been shown through analytical prowess that this specific geometry can be treated as a planar case of the Child-Langmuir law with only a 6% deviation from the cylindrical case. Additionally, magnetostatic simulations with self consistent space charge emitting surfaces of the main switch using the Trak code are under way. It is hoped that the simulations will provide evidence in support of both the analytical derivations and experimental data. Finally, an improved design of the ICCD (containing 12 collectors in the axial direction) is presently being implemented.

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Emphasis/Nevada STDEM : user's guide : version 1.0

Coats, Rebecca S.; Pasik, Michael F.; Seidel, David B.

STDEM is the structured mesh time-domain electromagnetic and plasma physics component of Emphasis/Nevada. This report provides a guide on using STDEM. Emphasis, the electromagnetic physics analysis system, is a suite of codes for the simulation of electromagnetic and plasma physics phenomena. The time-dependent components of Emphasis have been implemented using the Nevada framework [1]. The notation Emphasis/Nevada is used to highlight this relationship and/or distinguish the time-dependent components of Emphasis. In theory the underlying framework should have little influence on the user's interaction with the application. In practice the framework tends to be more invasive as it provides key services such as input parsing and defines fundamental concepts and terminology. While the framework offers many technological advancements from a software development point of view, from a user's perspective the key benefits of the underlying framework are the common interface for all framework physics modules as well as the ability to perform coupled physics simulations. STDEM is the structured time-domain electromagnetic and plasma physics component of Emphasis/Nevada. STDEM provides for the full-wave solution to Maxwell's equations on multi-block three-dimensional structured grids using finite-difference time-domain (FDTD) algorithms. Additionally STDEM provides for the fully relativistic, self-consistent simulation of charged particles using particle-in-cell (PIC) algorithms.

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Results 1–25 of 29
Results 1–25 of 29