Heavy Ion Fusion Systems Assessment Research Articles

Particle Accelerators — Applications in Technology and Research

"Particle Accelerators — Applications in Technology and Research." Fusion Technology, 19(2), p. 395 Additional informationNotes on contributorsWilliam B. HerrmannsfeldtWilliam B. Herrmannsfeldt (PhD, physics, University of Illinois, 1958) has worked in accelerator physics at the Stanford Linear Accelerator Center since 1962. He is active in heavy ion fusion accelerator research and was chairman of the steering committee for the heavy ion fusion systems assessment program. His special interests include high intensity beam transport issues and the numerical simulation of accelerator components.

Authors

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U.S. Heavy-Ion Fusion Systems Assessment Project Overview

A multi-institutional study was conducted to evaluate the potential of heavy-ion induction Linacs as inertial confinement fusion (ICF) drivers. This Heavy-Ion Fusion Systems Assessment (HIFSA) study was a U.S. effort to evaluate a wide range of possible system configurations for electric power plants driven by induction Linacs, as opposed to the radio-frequency accelerators used in previous heavy-ion fusion (HIF) power plant conceptual designs. In contrast to these earlier studies, the HIFSA project specifically avoided concentrating on a point design. Rather, cost/performance models of the major systems in an HIF power plant were devised by the institutions with expertise in the applicable technologies (e.g., Lawrence Berkeley Laboratory for induction accelerators and beam transport/focus; McDonnell Douglas Astronautics Company for cost scaling and systems modeling/intergration). (Detailed descriptions of these systems and associated integration/trade-off studies appear in other papers in this special issue.) Some of the key results of the HIFSA study are summarized and their significance assessed. The cardinal conclusions of the study are twofold: (a) Conceptual HIF power plants have estimated cost-of-electricity (COE) values that, at 1 GW (electric), are roughly comparable to those from other ICF and magnetic fusion system studies; and (b) HIF technology is robust in that there existsmore » a large parameter space region in which the COE is close to the minimum; i.e., the minima in COE are broad.« less

Targets for Heavy-Ion Fusion

This summary gives the motivation for the study of improved target concepts to be used in the ''Heavy Ion Fusion Systems Assessment Project.'' The target concepts that have been studied are listed.

Heavy-Ion Fusion Systems Assessment Implications for Reactors

The requirements, desirable characteristics, trade-offs, and design constraints are discussed for commercial heavy-ion fusion (HIF) reactor plants with induction linear accelerator (Linac) drivers. The trade-offs and the design constraints when the reactor plant requirements and desirable characteristics conflict with those for other HIF power plant systems are described. The reactor plant concepts included in the Heavy-Ion Fusion Systems Assessment (HIFSA) are discussed in relation to these requirements, characteristics, trade-offs, and constraints. Four reactor plant concepts were included in the HIFSA studies to provide large ranges of reactor repetition rate and target yield accommodation (1 to 20 Hz and 150 to 3000 MJ). This permitted thorough exploration of the impact on HIF cost of electricity (COE) of the high repetition rate and efficiency advantages of induction Linacs. Contrary to pre-HIFSA expectations, large plants with large driver repetition rates and multiple reactors are not required for attractive COE: Repetition rates <10 Hz in 1000-MW(electric) one-reactor plants are competitive. More than one HIF reactor plant concept shows promise: The minimum COE estimates for the four concepts in 1000-MW(electric) plants range from 55 to 75 mill/kW-h. Cost and/or technological problems in one part of reactor operating parameter space need not be fatal for HIF: The estimated COE is within 5% of the minimum over wide ranges of the repetition rate and the target yield for a fixed plant size and reactor concept.

Directions for reactor target design based on the U.S. Heavy Ion Fusion Systems Assessment

The Heavy-Ion Fusion Systems Assessment project is nearing completion of a two-year effort. The resulting system modelwill be used to set directions for future target design work.Major uncertainties in target design were studied using thecost of electricity as a figure of merit. Net electric power was fixed at 1000 MW to eliminate large effects due to economies of scale. The system is relatively insensitive to target gain, factors of three changes in gain resulting in 8 to 12% changes in electricity cost. Possible increased peak power requirements pose only a small cost risk, but require many more beamlets for transport. A shortening ofthe required ion range causes both cost and beamlet difficulties. A factor of 4 decrease in the required range at a fixed driver energy increases electricity cost by 44% and raises the number of beamlets to 240. Finally, the heavy ion fusion system can accommodate large increases in target costs. Thus, to address the major uncertainties, target design should concentrate on requirements for ion range andpeak driver power.

Heavy-Ion Fusion: Setting the Stage

The purpose of this paper is to establish the context on which the rest of this session will be based. Several papers will report work inspired by the Heavy-Ion Fusion Systems Assessment (HIFSA) Project. This is a small project that is about 2 years old. It is a small fraction of the Heavy-Ion Fusion (HIF) Program, which is itself very small compared to virtually any other fusion effort. Certainly, part of the basis for HIFSA lies in the history of HIF. The program was invented in high-energy physics accelerator laboratories in about 1975. In the past decade, work at several U.S. laboratories and universities, and in Japan and Europe, has resulted in fundamental understanding of the phenomena involved in the stable transport and acceleration of space charge limited beams. HIF is the approach that is, more than any other, most suited to the high energy (multi-megajoule), high repetition rate, and high efficiency required of a power plant driver. There have been seven international conferences devoted to HIF (most recently in May 1986) and numerous independent reviews. All of these confirm the promise of HIF for eventual use for commercial power production. Perhaps the best overall systems study for inertial fusionmore » to date, certainly the best for HIF, is the HIBAll-II study. In this study, the authors arrive at a power plant scenario in which they project a cost of electricity that is somewhat lower than that found for various magnetic fusion scenarios. Certainly it is competitive with magnetic fusion.« less

Heavy-Ion Fusion: Future Promise and Future Directions

The previous papers in this heavy-ion fusion special session have described work performed as part of the Heavy-Ion Fusion Systems Assessment (HIFSA) Project. Key technical issues in the design and costing of targets, induction linacs, beam transport, reactor, balance of plant, and systems integration have been identified and described. The HIFSA systems model was used to measure the relative value of improvements in physics understanding and technology developments in many different areas. Within the limits of our 1986 knowledge and imagination, this study defines the most attractive heavy-ion fusion (HIF) power plant concepts. The project has deliberately avoided narrowing the focus to a point facility design; thus, the generic systems modeling capability developed in the process allows for relative comparisons among design options. We will describe what are thought to be achievable breakthroughs and what the relative significance of the breakthroughs will be, although the specific mechanism for achieving some breakthroughs may not be clear at this point. This degree of optimism concerning such breakthroughs is probably at least as conservative as that used in other fusion assessments.

Reactor Designs for Heavy-Ion Fusion

The Heavy-Ion Fusion Systems Assessment (HIFSA) Project is a study of the prospects for successful pure fusion commercial HIF electric power generation using heavy-ion induction linear accelerator (linac) drivers. Although the project is led by Los Alamos National Lab. (LANL), success requires substantial contributions from all members of a large interdisciplinary team representing a unique assemblage of talent from other national laboratories, universities, and industry. The four reactor concepts included in the HIFSA studies - CASCADE, HYLIFE, wetted-wall, and magnetically protected - can be coupled with heavy-ion induction linacs operating over a wide range of pulse repetition rates to permit thorough exploration of the potential advantages of induction linacs as drivers. These concepts incorporate several interesting options, including solid and liquid-metal blankets and first-wall protection concepts, conventional and advanced power generation cycles, etc. No substantive obstacles to adaptation of these laser fusion reactor concepts for HIF have yet been identified. In particular, the reactor/driver interfaces and achievement of the lower cavity atmosphere densities required for HIF and the reactor/driver interfaces do not present significant problems.

A Systems Performance and Cost Model for Heavy Ion Fusion

As a part of the DOE-sponsored Heavy Ion Fusion Systems Assessment (HIFSA) project, a systems and costing computer model has been developed to examine the behavior of a linear induction accelerator-driven (LINAC) HIF power plant. The main purpose of this code is to examine different system and subsystem options as well as a large range of parameter space in which an HIF power plant might operate. The ultimate goals include the identification of: (1) desirable operating regimes, (2) preferred system and subsystem options, (3) systems with major cost impacts, and (4) systems where appropriate research and development or technological breakthroughs could yield significant economic benefits.The Inertial Confinement Systems and Costing Model (“ICCOMO”) is divided into six main sections: target design; cavity design; beam transport and final focus; linac design; plant power balance; and power plant costing. These routines are controlled by an overall driver which determines system inputs and contains parameter search and optimization capabilities. The target, cavity and beam transport sections each have the capability to model several different options. There are currently six target designs (two singleshell/2-sided illumination schemes; a doubleshell/2-sided illumination scheme; and three innovative designs), and four cavity designs (lithium waterfall, liquid lithium film, magnetically-protected dry wall and granular lithium compound). The target and cavity designs can be paired in a variety of ways. The beam transport option (single-beam, dual-beam and multiple-beam) appropriate to the particular target under consideration is used.The linac design consists of a set of curve fits to data produced by the Lawrence Berkeley Laboratory linac design code, LIACEP. These curve fits model accelerator cost, efficiency and length as a function of a variety of system inputs and target requirements. The plant power balance routine computes gross electric power, recirculating power requirements and net electric power output. If a specific net electric power is desired, the thermal power is adjusted iteratively until convergence is achieved. Finally, the power plant costing routine produces direct and indirect capital costs, operating costs and the resulting cost of electricity based upon the assumption of a tenth-of-a-kind power plant with commercially developed components. Steam, liquid metal or helium coolant cycles are combined with compatible cavity designs. Conventional balance-of-plant technology is generally assumed.This code is currently being exercised in order to locate the preferred operating regime for net electric powers in the range of 1000-2000 MWe HIF commercial power plants. Trade studies that are currently being performed include variation of repetition rate; target type; target parameters; targetillumination scheme; cavity type; number ofreactor cavities; and accelerator parameters.Preliminary results at 1000 MWe indicate that targets with gains of about 100 and driver repetition rates around 5 Hz are preferable. However, overall power plant costs of electricity appear to be relatively insensitive to parameters such as target type, gamma (r3/2R where r is beam spot radius and R is ion range) and accelerator ion species. Both capital costs and cost of electricity appear to be minimized at medium beam energies and high ion voltages (§5 MJ and 15 GeV respectively). Single reactor cavities tend to be preferable to multiple cavities, although the cost of electricity is relatively insensitive to the number of cavities in most operating regimes. Predictably, 2000 MWe power plants yield much lower costs of electricity, demonstrating the preference of the linac driver for operation at higher beam energies and the general economies of scale inherent in larger power plants.

Targets for Heavy Ion Fusion

This summary gives the motivation for the study of improved target concepts to be used in the ''Heavy Ion Fusion Systems Assessment Project.'' The target concepts that have been studied are listed.