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Heavy ion fusion experiments at LBNL and LLNL

Description: The long-range goal of the US Heavy Ion Fusion (HIF) program is to develop heavy ion accelerators capable of igniting inertial fusion targets to generate fusion energy for electrical power production. Accelerators for heavy ion fusion consist of several subsystems: ion sources, injectors, matching sections, combiners, induction acceleration sections with electric and magnetic focusing, beam compression and bending sections, and a final-focus system to focus the beams onto the target. We are currently assembling or performing experiments to address the physics of all these subsystems. This paper will discuss some of these experiments.
Date: August 19, 1998
Creator: Ahle, L
Partner: UNT Libraries Government Documents Department

Systems modeling for heavy ion drivers - an induction linac example

Description: A source-to-target model for a induction linac driver for heavy ion fusion has been developed and is described here. Design features for a reference case driver that meets the requirements of one current target design are given, and the systems analyses supporting the point design are discussed. Directions for future work are noted.
Date: September 30, 1997
Creator: Meier, W.R.; Bangerter, R.O. & Faltens, A.
Partner: UNT Libraries Government Documents Department

Systems modeling and analysis of heavy ion drivers for inertial fusion energy

Description: A computer model for systems analysis of heavy ion drivers based on induction linac technology has been used to evaluate driver designs for inertial fusion energy (IFE). Design parameters and estimated costs have been determined for drivers with various ions, different charge states, different front-end designs, with and without beam merging, and various pulse compression and acceleration schedules. We have examined the sensitivity of the results to variations in component cost assumptions, design constraints, and selected design parameters
Date: June 3, 1998
Creator: Meier, W. R.
Partner: UNT Libraries Government Documents Department

Manipulation of high-current pulses for heavy-ion fusion

Description: For efficient induction-driven heavy-ion fusion, the current profile along a pulse must be modified in a non-selfsimilar manner between the accelerator and the target. In the accelerator, the pulse should have a duration of at least 50 ns in order to make efficient use of the induction cores, and the current should by nearly uniform along the pulse to minimize the aperture. In contrast, the optimal current profile on target consists of a main pulse of about 10 ns preceded by a longer low-current `foot.` This pulse-shape manipulation must be carried out at the final pulse energy (5-10 GeV for 200 amu ions) in the presence of a large nonlinear longitudinal space-charge field. A straightforward method is presented here for doing the required pulse shaping. Induction-ceU voltages are generated using idealized beam profiles both in the accelerator and on target, and they are verified and checked for error sensitivity using the fluid/envelope code CIRCE.
Date: October 28, 1996
Creator: Sharp, W.M.; Callahan, D.A.; Griedman, A. & Grote, D.P.
Partner: UNT Libraries Government Documents Department

An integrated systems model for heavy ion drivers

Description: A source-to-target computer model for an induction linac driver for heavy ion fusion has been developed and used to define a reference case driver that meets the requirements of one current target design. Key features of the model are discussed, and the design parameters of the reference case design are described. Examples of the systems analyses leading to the point design are given, and directions for future work are noted.
Date: September 2, 1998
Creator: Bangerter, R O; Faltens, A & Meier, W R
Partner: UNT Libraries Government Documents Department

Generating High-Brightness Light Ion Beams for Inertial Fusion Energy

Description: Light ion beams may be the best option for an Inertial Fusion Energy (IFE) driver from the standpoint of ei%ciency, standoff, rep-rate operation and cost. This approach uses high-energy-density pulsed power to efficiently accelerate ions in one or two stages at fields of 0.5 to 1.0 GV/m to produce a medium energy (30 MeV), high-current (1 MA) beam of light ions, such as lithium. Ion beams provide the ability for medium distance transport (4 m) of the ions to the target, and standofl of the driver from high- yield implosions. Rep-rate operation of' high current ion sources has ako been demonstrated for industrial applications and couId be applied to IFE. Although (hese factors make light ions the best Iong-teml pulsed- power approach to IFE, light-ion research is being suspended this year in favor of a Z-pinch-driven approach which has the best opport lnity to most-rapidly achieve the U.S. Department of Energy sponsor's goal of high-yield fusion. This paper will summarize the status and most recent results of the light-ion beam program at Sandia National Laboratories (SNL), and document the prospects of light ions for future IFE driver development.
Date: October 22, 1998
Creator: Adams, R.G.; Bailey, J.E.; Cuneno, M.E.; Desjarlais, M.P.; Filuk, A.B.; Hanson, D.L. et al.
Partner: UNT Libraries Government Documents Department

Beam dynamics in heavy ion fusion

Description: A standard design for heavy ion fusion drivers under study in the US is an induction linac with electrostatic focusing at low energy and magnetic focusing at higher energy. The need to focus the intense beam to a few-millimeter size spot at the deuterium-tritium target establishes the emittance budget for the accelerator. Economic and technological considerations favor a larger number of beams in the low-energy, electrostatic-focusing section than in the high-energy, magnetic-focusing section. Combining four beams into a single focusing channel is a viable option, depending on the growth in emittance due to the combining process. Several significant beam dynamics issues that are, or have been, under active study are discussed: large space charge and image forces, beam wall clearances, halos, alignment, longitudinal instability, and bunch length control.
Date: April 1, 1995
Creator: Seidl, P.
Partner: UNT Libraries Government Documents Department

Heavy ion beam transport in an inertial confinement fusion reactor

Description: A new code, bimc, is under development to determine if a beam of heavy ions can be focused to the necessary spot-size radius of about 2 mm within an inertial confinement reactor chamber where the background gas densities are on the order of 10{sup 14}--10{sup 15} cm{sup {minus}3} Lithium (or equivalent). Beam transport is expected to be strongly affected by stripping and collective plasma phenomena; however, if propagation is possible in this regime, it could lead to simplified reactor designs. The beam is modeled using a 2 1/2 D particle-in-cell (PIC) simulation code coupled with a Monte Carlo (MC) method for analyzing collisions. The MC code follows collisions between the beam ions and neutral background gas atoms that account for the generation of electrons and background gas ions (ionization), and an increase of the charge state of the beam ions (stripping). The PIC code models the complete dynamics of the interaction of the various charged particle species with the self generated electromagnetic fields. Details of the code model and preliminary results are presented.
Date: August 1, 1995
Creator: Barboza, N.
Partner: UNT Libraries Government Documents Department

Experimental investigations of plasma lens focusing and plasma channel transport of heavy ion beams

Description: Final focusing of ion beams and propagation in a reactor chamber are crucial questions for heavy ion beam driven Fusion. An alternative solution to ballistic quadrupole focusing, as it is proposed in most reactor studies today, is the utilization of the magnetic field produced by a high current plasma discharge. This plasma lens focusing concept relaxes the requirements for low emittance and energy spread of the driver beam significantly and allows to separate the issues of focusing, which can be accomplished outside the reactor chamber, and of beam transport inside the reactor. For focusing a tapered wall-stabilized discharge is proposed, a concept successfully demonstrated at GSI, Germany. For beam transport a laser pre-ionized channel can be used.
Date: April 1, 1995
Creator: Tauschwitz, T.; Yu, S.S.; Eylon, S.; Reginato, L.; Leemans, W.; Rasmussen, J.O. et al.
Partner: UNT Libraries Government Documents Department

Design and construction of a large aperture, quadrupole electromagnet prototype for ILSE

Description: We are currently constructing a prototype quadrupole electromagnet for the proposed Induction Linac Systems Experiment (ILSE) at LBL. ILSE will address many physi and engineering issues relevant to the design of a heavy-ion fusion driver accelerator. The pulsed electromagnet has two layers of current windings and will produce a field gradient exceeding 25 T/m at a repetition rate of 1 Hz steady-state. In this paper, we discuss how the interaction of various concerns such as maximum dynamic aperture, short lattice period, field quality, iron yoke weight, heat transfer, and voltage standoff have led to our particular design choices. We also present 2- and 3-D numerical calculations concerning field topography and the results of transport simulations of space-charge dominated ion beams with ILSE parameters.
Date: April 1, 1995
Creator: Stuart, M.; Faltens, A.; Fawley, W.M.; Peters, C. & Vella, M.C.
Partner: UNT Libraries Government Documents Department

The light ion LMF and its relevance to IFE

Description: The inertial confinement fusion (ICF) program at Sandia National Laboratories (SNL) is directed toward validating light ions as an efficient driver for ICF defense and energy applications. The light ion laboratory microfusion facility (LMF) is envisioned as a facility in which high gain ICF targets could be developed and utilized in defense-related experiments. The relevance of LMF technology to eventual inertial fusion energy (IFE) applications is assessed via a comparison of LMF technologies with those projected in the Light Ion Beam Reactor Assessment (LIBRA) conceptual reactor design study.
Date: December 1, 1993
Creator: Olson, R. E.; Allshouse, G. O.; Cook, D. L.; Lockner, T. R.; Mazarakis, M. G.; Olson, C. L. et al.
Partner: UNT Libraries Government Documents Department

Heavy-ion fusion driver research at Berkeley and Livermore

Description: The Department of Energy is restructuring the U.S. fusion program to place a greater emphasis on science. As a result, we will not build the ILSE or Elise heavy ion fusion (HIF) facilities described in 1992 and 1994 conferences. Instead we are performing smaller experiments to address important scientific questions. Accelerator technology for HIF is similar to that for other applications such as high energy physics and nuclear physics. The beam physics, however, differs from the physics encountered in most accelerators, where the pressure arising from the beam temperature (emittance) is the dominant factor determining beam size and focusing system design. In HIF, space charge is the dominant feature, leading us into a parameter regime where.the beam plasma frequency becomes comparable to the betatron frequency. Our experiments address the physics of non-neutral plasmas in this novel regime. Because the beam plasma frequency is low, Particle-in-cell (PIC) simulations provide a good description of most of our experiments. Accelerators for HIF consist of several subsystems: ion sources, injectors, matching sections, combiners, acceleration sections with electric and magnetic focusing, beam compression and bending sections, and a system to focus the beams onto the target. We are currently assembling or performing experiments to address the physics of all these subsystems. This paper will discuss experiments in injection, combining, and bending.
Date: August 1, 1996
Creator: Seidl, P.; Bangerter, R. & Celata, C.M.
Partner: UNT Libraries Government Documents Department

Workshop on transport for a common ion driver

Description: This report contains research in the following areas related to beam transport for a common ion driver: multi-gap acceleration; neutralization with electrons; gas neutralization; self-pinched transport; HIF and LIF transport, and relevance to common ion driver; LIF and HIF reactor concepts and relevance to common ion driver; atomic physics for common ion driver; code capabilities and needed improvement.
Date: December 31, 1994
Creator: Olson, C.C.; Lee, E. & Langdon, B.
Partner: UNT Libraries Government Documents Department

Progress in heavy-ion drivers for inertial fusion

Description: Heavy-ion induction accelerators are being developed as fusion drivers for ICF power production in the US Inertial Fusion Energy (IFE) program, in the Office of Fusion Energy of the US Department of Energy. In addition, they represent an attractive driver option for a high-yield microfusion facility for defense research. This paper describes recent progress in induction drivers for Heavy-Ion Fusion (HIF), and plans for future work. It presents research aimed at developing drivers having reduced cost and size, specifically advanced induction linacs and recirculating induction accelerators (recirculators). The goals and design of the Elise accelerator being built at Lawrence Berkeley Laboratory (LBL), as the first stage of the ILSE (Induction Linac Systems Experiments) program, are described. Elise will accelerate, for the first time, space-charge-dominated ion beams which are of full driver scale in line-charge density and diameter. Elise will be a platform on which the critical beam manipulations of the induction approach can be explored. An experimental program at Lawrence Livermore National Laboratory (LLNL) exploring the recirculator principle on a small scale is described in some detail; it is expected that these studies will result ultimately in an operational prototype recirculating induction accelerator. In addition, other elements of the US HIF program are described.
Date: December 22, 1994
Creator: Friedman, A.; Bangerter, R.O. & Herrmannsfeldt, W.B.
Partner: UNT Libraries Government Documents Department

Heavy ion beam propagation through a gas-filled chamber for inertial confinement fusion

Description: The work presented here evaluates the dynamics of a beam of heavy ions propagating through a chamber filled with gas. The motivation for this research stems from the possibility of using heavy ion beams as a driver in inertial confinement fusion reactors for the purpose of generating electricity. Such a study is important in determining the constraints on the beam which limit its focus to the small radius necessary for the ignition of thermonuclear microexplosions which are the source of fusion energy. Nuclear fusion is the process of combining light nuclei to form heavier ones. One possible fusion reaction combines two isotopes of hydrogen, deuterium and tritium, to form an alpha particle and a neutron, with an accompanying release of {approximately}17.6 MeV of energy. Generating electricity from fusion requires that we create such reactions in an efficient and controlled fashion, and harness the resulting energy. In the inertial confinement fusion (ICF) approach to energy production, a small spherical target, a few millimeters in radius, of deuterium and tritium fuel is compressed so that the density and temperature of the fuel are high enough, {approximately}200 g/cm{sup 3} and {approximately}20 keV, that a substantial number of fusion reactions occur; the pellet microexplosion typically releases {approximately}350 MJ of energy in optimized power plant scenarios.
Date: October 1, 1996
Creator: Barboza, N.O.
Partner: UNT Libraries Government Documents Department

Chamber propagation physics for heavy ion fusion

Description: Chamber transport is an important area of study for heavy ion fusion. Final focus and chamber-transport are high leverage areas providing opportunities to significantly decrease the cost of electricity from a heavy ion fusion power plant. Chamber transport in two basic regimes is under consideration. In the low chamber density regime ({approx_lt}0.003 torr), ballistic or nearly-ballistic transport is used. Partial beam neutralization has been studied to offset the effects of beam stripping. In the high chamber density regime ({approx_gt}.1 torr), two transport modes (pinched transport and channel transport) are under investigation. Both involve focusing the beam outside the chamber then transporting it at small radius ({approx} 2 mm). Both high chamber density modes relax the constraints on the beam quality needed from the accelerator which will reduce the driver cost and the cost of electricity.
Date: September 1, 1995
Creator: Callahan, D.A.
Partner: UNT Libraries Government Documents Department

Perfect 2-d quadrupole fields from permanent magnets

Description: Consider the 13-beam channel array shown in Figure 1. It is asserted that, under mathematically ideal assumptions, a pure quadrupole field is centered in each of the 13 beam channel boxes. An identical quadrupole field (for {bar H}, not {bar B}) is also centered in each of the 4 boxes containing 4 magnetic wedges located near the center of the system. An iron yoke ({mu} = {infinity}) with the displayed zig-zag shape provides a boundary condition (H{sub {parallel}} = 0) that makes the 13 channels equivalent to a portion of an infinite array. A similar array can be readily drawn for any number of beams. The quadrupole gradient in the beam channels is B{prime} = M{sub o}/2b, where M{sub o} is the remnant field of the magnetic wedges, and the channel diameter (wedge-to-wedge) is 2b. Note that a unit cell of the array, containing one beam, has diameter 2{radical}2 b (viewed from 45{degree} tilt) so its area is 8 b{sup 2}. A significant advantage of this design over those using dipolar blocks is the large fraction of cross section devoted to beam channels (50% vs 25%). Application to a heavy ion fusion driver is discussed.
Date: April 1, 1996
Creator: Lee, E.P. & Vella, M.
Partner: UNT Libraries Government Documents Department

Overview of the WARP code and studies of transverse resonance effects

Description: Two papers presented at the Shelter Island workshop are very briefly summarized here, in view of recent publications elsewhere The WARP code, developed for Heavy-Ion beam-driven inertial confinement Fusion (HIF) accelerator studies, combines features of a particle-in-cell plasma simulation and an accelerator tracking program. Its methods and architecture have been developed for efficiency both in detailed simulation of individual machine sections and in long-time beam tracking. The transverse ``slice`` model in the code has been applied to the study of transverse resonance effects associated with quadrupole strength errors. These simulations confirm that rapid passage through a resonance can reduce the associated mismatch and emittance growth References to published details and to other sources of information are supplied.
Date: May 1, 1998
Creator: Friedman, A., LLNL
Partner: UNT Libraries Government Documents Department

Numerical simulation studies of the LBNL heavy-ion beam combiner experiment

Description: Transverse beam combining is a cost-saving option employed in many designs for heavy-ion inertial fusion energy drivers. A major area of interest, both theoretically and experimentally, is the resultant transverse phase space dilution during the beam merging process. Currently, a prototype combining experiment is underway at LBNL and we have employed a variety of numerical descriptions to aid in both the initial design of the experiment data. These range from simple envelope codes to detailed 2- and 3-D PIC simulations. We compare the predictions of the different numerical models to each other and to experimental data at different longitudinal positions.
Date: January 1, 1997
Creator: Fawley, W.M.; Seidl, P.; Haber, I.; Friedman, A. & Grote, D.P.
Partner: UNT Libraries Government Documents Department

Selection of IFE target materials from a safety and environmental perspective

Description: Target materials for inertial fusion energy (IFE) power plant designs might be selected for a wide variety of reasons including wall absorption of driver energy, material opacity, cost, and ease of fabrication. While each of these issues are of great importance, target materials should also be selected based upon their safety and environmental (S and E) characteristics. The present work focuses on the recycling, waste management, and accident dose characteristics of potential target materials. If target materials are recycled so that the quantity is small, isotopic separation may be economically viable. Therefore, calculations have been completed for all stable isotopes for all elements from lithium to polonium. The results of these calculations are used to identify specific isotopes and elements that are most likely to be offensive as well as those most likely to be acceptable in terms of their S and E characteristics.
Date: March 1, 2000
Creator: Latkowski, J F; Reyes, S; Sanz, J & Gomez del Rio, J
Partner: UNT Libraries Government Documents Department

Developing high brightness beams for heavy ion driven inertial fusion

Description: Heavy ion fusion (HIF) drivers require large currents and bright beams. In this paper we review the two different approaches for building HIF injectors and the corresponding ion source requirements. The traditional approach uses large aperture, low current density ion sources, resulting in a very large injector system. A more recent conceptual approach merges high current density mini-beamlets into a large current beam in order to significantly reduce the size of the injector. Experiments are being prepared to demonstrate the feasibility of this new approach.
Date: August 29, 2001
Creator: Kwan, J.W.; Ahle, L.A.; Anders, A.; Bieniosek, F.M.; Chacon-Golcher, E.; Grote, D.P. et al.
Partner: UNT Libraries Government Documents Department

Heavy ion fusion experiments at LLNL

Description: We review the status of the experimental campaign being carried out at Lawrence Livermore National Laboratory, involving scaled investigations of the acceleration and transport of space-charge dominated heavy ion beams. The ultimate goal of these experiments is to help lay the groundwork for a larger scale ion driven inertial fusion reactor, the purpose of which is to produce inexpensive and clean electric power.
Date: February 6, 1996
Creator: Barnard, J.J.; Cable, M.D. & Callahan, D.A.
Partner: UNT Libraries Government Documents Department

The light ion pulsed power induction accelerator for ETF

Description: Our Engineering Test Facility (ETF) driver concept is based on HERMES III and RHEPP technologies. Actually, it is a scaled-down version of the LMF design incorporating repetition rate capabilities of up to 10 Hz CW. The preconceptual design presented here provides 200-TW peak power to the ETF target during 10 ns, equal to 2-MJ total ion beam energy. Linear inductive voltage addition driving a self-magnetically insulated transmission line (MITL) is utilized to generate the 36-MV peak voltage needed for lithium ion beams. The {approximately} 3-MA ion current is achieved by utilizing many accelerating modules in parallel. Since the current per module is relatively modest ({approximately}300 kA), two-stage or one-stage extraction diodes can be utilized for the generation of singly charged lithium ions. The accelerating modules are arranged symmetrically around the fusion chamber in order to provide uniform irradiation onto the ETF target. In addition, the modules are fired in a programmed sequence in order to generate the optimum power pulse shape onto the target. This design utilizes RHEPP accelerator modules as the principal power source.
Date: December 31, 1994
Creator: Mazarakis, M.G.; Olson, R.E.; Olson, C.L.; Smith, D.L. & Bennett, L.F.
Partner: UNT Libraries Government Documents Department

Induction Linac Systems Experiments for heavy ion fusion

Description: The Lawrence Berkeley Laboratory and the Lawrence Livermore National Laboratory propose to build at LBL the Induction Linac Systems Experiments (ILSE), the next logical step toward the eventual goal of a heavy ion induction accelerator powerful enough to implode or drive inertial confinement fusion targets. Though much smaller than a driver, ILSE will be at full driver scale in several important parameters. Nearly all accelerator components and beam manipulations required for a driver will be tested. It is expected that ILSE will be built in stages as funds and technical progress allow. The first stage, called Elise will include all of the electrostatic quadrupole focused parts of ILSE.
Date: June 1994
Creator: Herrmannsfeldt, W. B. & Bangerter, R. O.
Partner: UNT Libraries Government Documents Department