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Power-Amplification of a Heavy-Ion Beam in an InductionLinac

Description: In contrast to an rf linac - a constant-current device in which the beam power is increased solely by the addition of kinetic energy, qV, - the induction linac (I.L.) can amplify the beam power at a much more rapid rate. Proper programming of the switching of the modules and the shape of their voltage waveforms, in the early stages o f acceleration, can result in a beam current that rises at a rate between v{sup 1/2} and V and, consequently, a beam power that varies in the range v{sup 3/2} to v{sup 2}. The current is limited by the transport lens system, which must overcome the beam defocusing force due to space charge.
Date: September 1, 1983
Creator: Faltens, A. & Keefe, D.
Partner: UNT Libraries Government Documents Department

Investigation of Re-X glass ceramic for acceleration insulating columns

Description: In an induction linac the accelerating voltage appears along a voltage-graded vacuum insulator column which is a performance limiting and major cost component. Re-X glass ceramic insulators have the long-sought properties of allowing cast-in gradient electrodes, good breakdown characteristics, and compatibility with high vacuum systems. Re-X is a glass ceramic developed by General Electric for use in the manufacture of electrical apparatus, such as vacuum arc interrupters. We have examined vacuum outgassing behavior and voltage breakdown in vacuum and find excellent performance. The housings are in the shape of tubes with type 430 stainless steel terminations. Due to a matched coefficient of thermal expansion between metal and insulator, no vacuum leaks have resulted from any welding operation. The components should be relatively inexpensive to manufacture in large sizes and appear to be a very attractive accelerator column. We are planning to use a standard GE housing in our MBE-4 induction linac.
Date: May 1, 1985
Creator: Faltens, A. & Rosenblum, S.
Partner: UNT Libraries Government Documents Department

Applications of induction linac technology to heavy ion fusion

Description: Evaluation of the application of heavy ion accelerators to ignite d-t pellets in a thermonuclear reactor is discussed. Accelerator design requirements considered include transport-limited current, beam injection conditions, and pulse bunching and focusing characteristics. The desirability of resonant and non-resonant accelerating structures is comparatively examined. The required power system switch tubes are discussed. It is concluded that heavy ion accelerators could offer a promising solution to the pellet-igniter problem. The advantages pointed out for this approach include electric efficiency greater than 10 percent, the possibility of high repetition rates (1 to 10 Hz), and a mature technological base. (RME)
Date: July 1, 1977
Creator: Faltens, A. & Keefe, D.
Partner: UNT Libraries Government Documents Department

Review of induction LINACS

Description: There has been a recent upsurge of activity in the field of induction linacs, with several new machines becoming operational and others in the design stages. The performance levels of electron machines have reached 10's of kiloamps of current and will soon reach 10's of MeV's of energy. Acceleration of ion current has been demonstrated, and the study of a 10 GeV heavy ion induction linac for ICF continues. The operating principles of induction linacs are reviewed with the emphasis on design choices which are important for increasing the maximum beam currents.
Date: October 1, 1981
Creator: Faltens, A. & Keefe, D.
Partner: UNT Libraries Government Documents Department

Quasi-static drift-tube accelerating structures for low-speed heavy ions

Description: The major attractions of the pulsed drift-tubes are that they are non-resonant structures and that they appear suitable for accelerating a very high current bunch at low energies. The mechanical tolerances of the non-resonant structure are very loose and the cost per meter should be low; the cost of the transport system is expected to be the major cost. The pulse power modulators used to drive the drift-tubes are inexpensive compared to r.f. sources with equivalent peak-power. The longitudinal emittance of the beam emerging from the structure could be extremely low.
Date: November 3, 1977
Creator: Faltens, A. & Keefe, D.
Partner: UNT Libraries Government Documents Department

Power-amplification of a heavy-ion beam in an induction linac

Description: In contrast to an rf linac - a constant-current device in which the beam power is increased solely by the addition of kinetic energy, qV, - the induction linac (I.L.) can amplify the beam power at a much more rapid rate. Proper programming of the switching of the modules and the shape of their voltage waveforms, in the early stages of acceleration, can result in a beam current that rises at a rate between V/sup 1/2/ and V and, consequently, a beam power that varies in the range V/sup 3/2/ to V/sup 2/. The current is limited by the transport lens system, which must overcome the beam defocusing force due to space charge.
Date: September 1, 1983
Creator: Faltens, A. & Keefe, D.
Partner: UNT Libraries Government Documents Department

Heavy-Ion Fusion System Assessment Project quarterly status report, January-March 1985

Description: A computer model of an accelerator system is a necessary ingredient in estimating the cost of construction and operation of an ion-driven ICF power plant. The LBL computer program LIACEP (Linear Induction Accelerator Cost Evaluation Program) is used to estimate the cost and efficiency of a heavy ion induction linear accelerator as a function of the ion mass, charge and energy for a specified beam output energy, power and pulse repetition frequency. In addition to estimating the accelerator system cost and efficiency, LIACEP can be used to identify the components and materials that have a high leverage on the cost and efficiency of the accelerator system. These high leverage items are logical areas for research and technology development to reduce the cost and increase the efficiency of the accelerator system.
Date: June 1, 1985
Creator: Lee, E.P.; Hovingh, J. & Faltens, A.
Partner: UNT Libraries Government Documents Department

3-megajoule heavy-ion fusion driver

Description: The initiation of inertial confinement fusion reactions with a heavy ion particle beam has been under intensive study since 1976, and the progress of this study is principally documented in the proceedings of annual workshops held by US National Laboratories. At this time a 3MJ, 150 TW, ion beam is a good choice to initiate microexplosions with energy gain of 100. The Lawrence Berkeley Laboratory has made systems studies based on a Linear Induction Accelerator to meet the beam requirements. The accelerator system, expected performance and cost, and technical problems to be addressed in the near future are discussed.
Date: June 1, 1981
Creator: Faltens, A.; Hoyer, E. & Keefe, D.
Partner: UNT Libraries Government Documents Department

Induction accelerator test module for HIF

Description: An induction linac test module suitable for investigating the drive requirements and the longitudinal coupling impedance of a high-power ion induction linac has been constructed by the Heavy Ion Fusion (HIF) group at LBL. The induction linac heavy ion driver for inertial confinement fusion (ICF) as presently envisioned uses multiple parallel beams which are transported in separate focusing channels but accelerated together in the induction modules. The resulting induction modules consequently have large beam apertures-1--2 meters in diameter- and correspondingly large outside diameters. The module geometry is related to a low-frequency gap capacity'' and high-frequency structural resonances, which are affected by the magnetic core loading and the module pulser impedance. A description of the test module and preliminary results are presented. 3 figs.
Date: April 1, 1991
Creator: Faltens, A.
Partner: UNT Libraries Government Documents Department

Study of the beam breakup mode in linear induction accelerators for heavy ions

Description: A simple theoretical study and numerical estimate is presented for the transverse amplitude growth of a nonrelativistic heavy ion beam in an induction linac, as envisaged for use in commercial power plants, due to the nonregenerative coherent beam breakup mode. An equivalent electrical circuit has been used to represent the accelerating induction modules. Our calculation shows that for the parameters of interest, the beam breakup amplitude for a heavy ion beam grows extremely slowly in the time scales of interest, to magnitudes insignificant for transport purposes. It is concluded that the coherent beam breakup mode does not pose any serious threat to the stability of a high current (kA) heavy ion beam in an induction linac.
Date: March 1, 1981
Creator: Chattopadhyay, S.; Faltens, A. & Smith, L.
Partner: UNT Libraries Government Documents Department

Operating experience with a high-current Cs/sup +1/ injector for heavy-ion fusion

Description: The construction and assembly of a Cs ion injector consisting of a pulsed source and 3 pulsed drift tubes has been complete since April 1980. The measurement program, underway since then to characterize the beam, has been interspersed with the development of diagnostic equipment. The Cs contact ionization source and each of the 3 drift tubes are driven by 500 kV Marx generators. The injector has been operated reliably at 300 kV/stage at a repetition rate of 1 pulse/4 sec. About 10/sup 5/ pulses have been accumulated. The space charge limited diode and drift tube acceleration system were designed with the aid of the EGUN code of Herrmannsfeldt. Measurements of the beam envelope have been made by means of a movable biased charge collector. Good agreement with the EGUN calculation is found. Measurements of the beam emittance have been made at the exit of the third drift tube. The normalized emittance ..pi.. epsilon N = 2 x 10/sup -6/ ..pi.. m-rad is of better optical quality than that required for further acceleration and transport in a Heavy Ion Fusion (HIF) Induction Linac Driver.
Date: March 1, 1981
Creator: Chupp, W.; Faltens, A. & Herrmannsfeldt, W.
Partner: UNT Libraries Government Documents Department

Time Delays, Bends, Acceleration and Array Reconfigurations

Description: This note was originally one of the parts of the work on a 50 MeV and 500 MeV Rb{sup +} driver and part of work on delay lines for a 60 GeV U{sup +12} driver. It is slightly expanded here to make it more generally applicable. The emphasis is on beam manipulations such as joining and separating beams at the two ends of a driver and providing various time delays between beams as required by the target.
Date: June 24, 2011
Creator: Faltens, A.
Partner: UNT Libraries Government Documents Department

Comparison of the design and costs of induction linac drivers for inertial fusion using ions of mass 133 and 200

Description: Optimized cost estimates for induction linac accelerators using mass 133 ions at a charge state of +2 producing inertial fusion target yields of 300, 600, and 1200 MJ are presented. The ions are injected into the accelerator at 3 MV, and accelerated to the required voltage appropriate to the desired target yield. A cost comparison of these drivers is made with drivers using mass 200, charge state +3 ions for several target yields and a fusion power of 3000 MW.
Date: June 1, 1986
Creator: Hovingh, J.; Brady, V.O.; Faltens, A. & Lee, E.P.
Partner: UNT Libraries Government Documents Department

Comparison of the design and costs of induction linac drivers for inertial fusion using ions of differing mass

Description: An induction linear accelerator that produces an energetic (5 to 20 GeV) beam of heavy (130 to 238 amu) ions is a prime candidate as a driver for inertial fusion. The required accelerator output parameters for an ion species can be determined from the target requirements for a given fusion energy yield. The cost and efficiency of various accelerator configurations to produce the required output parameters can be determined to aid in the selection of the lowest cost accelerator design option. In this study, we compare the cost of various accelerator configurations that will produce various target fields and fusion powers using cesium 133 ions with those using mercury 200 ions, and report extensively on some 600 MJ target yield results.
Date: January 1, 1986
Creator: Hovingh, J.; Brady, V.O.; Faltens, A. & Lee, E.P.
Partner: UNT Libraries Government Documents Department

Development of electrostatic quadrupoles for heavy ion fusion

Description: High-voltage electrostatic quadrupoles are used for focusing ion beams at low energies in the induction linac approach to heavy ion driven inertial confinement fusion for the production of electrical power. The transportable beam line charge density depends linearly on the operating voltage of the quadrupoles, so an experimental program was conducted to find the voltage break-down dependence on the overall size of the quadrupoles which would then allow determination of the best geometry and operating voltage. The quadrupole electrodes are usually stainless steel cylinders with hemispherical end caps, mounted on stainless steel end plates. The end plates are precisely positioned with respect to each other and the vacuum chamber with alumina insulators with shielded triple points. It is advantageous for beam transport to employ an array of multiple beams for which a rather large number of interdigitated electrodes forms an array of quadrupoles. The trade-offs between very large numbers of small channels and a smaller number of large channels, and the dependence of the choice on the voltage break-down dependence is discussed. With present understanding, the optimum is about 100 beamlets focused with quadrupoles which have a beam aperture radius of about 2.3 cm and are operated with about 150 kV between electrodes.
Date: March 1, 1996
Creator: Faltens, A. & Seidl, P.
Partner: UNT Libraries Government Documents Department

Pulsed Drift Tube Accelerator

Description: The pulsed drift-tube accelerator (DTA) concept was revived by Joe Kwan and John Staples and is being considered for the HEDP/WDM application. It could be used to reach the full energy or as an intermediate accelerator between the diode and a high gradient accelerator such as multi-beam r.f. In the earliest LBNL HIF proposals and conceptual drivers it was used as an extended injector to reach energies where an induction linac with magnetic quadrupoles is the best choice. For HEDP, because of the very short pulse duration, the DTA could provide an acceleration rate of about 1MV/m. This note is divided into two parts: the first, a design based on existing experience; the second, an optimistic extrapolation. The first accelerates 16 parallel K{sup +} beams at a constant line charge density of 0.25{micro} C/m per beam to 10 MeV; the second uses a stripper and charge selector at around 4MeV followed by further acceleration to reach 40 MeV. Both benefit from more compact sources than the present 2MV injector source, although that beam is the basis of the first design and is a viable option. A pulsed drift-tube accelerator was the first major HIF experiment at LBNL. It was designed to produce a 2{micro}s rectangular 1 Ampere C{sub s}{sup +} beam at 2MeV. It ran comfortably at 1.6MeV for several years, then at lower voltages and currents for other experiments, and remnants of that experiment are in use in present experiments, still running 25 years later. The 1A current, completely equivalent to 1.8A K{sup +}, was chosen to be intermediate between the beamlets appropriate for a multi-beam accelerator, and a single beam of, say, 10A, at injection energies. The original driver scenarios using one large beam on each side of the reactor rapidly fell out of favor because of the ...
Date: October 25, 2004
Creator: Faltens, A.
Partner: UNT Libraries Government Documents Department

Long-pulse induction acceleration of heavy ions

Description: A long-pulse induction acceleration unit has been installed in the high-current Cs/sup +/ beam line at LBL and has accelerated heavy ions. A maximum energy gain of 250 keV for 1.5 ..mu..s is possible. The unit comprises 12 independent modules which may be used to synthesize a variety of waveforms by varying the triggering times of the low-voltage trigger generators.
Date: March 1, 1983
Creator: Faltens, A.; Firth, M.; Keefe, D. & Rosenblum, S.S.
Partner: UNT Libraries Government Documents Department

Design/cost of an induction linac for heavy ions for pellet-fusion

Description: The physics of the pellet implosion sets stringent conditions on the accelerator driver. The beam energy should be > 1 MJ, the beam power > 100 TW (implying a pulse length approx. = 10 ns), and the specific energy deposition in the pellet > 20 MJ/g. Thus, considerable current amplification is required, e.g. from some 10 amps at the source to perhaps 10 kiloamps at the pellet. Most of this amplification can be accomplished continuously along the accelerator and the remainder achieved at the end by bunching in the final transport lines to the target chamber. A conceptual schematic of an Induction Linac Fusion Driver is shown, which includes an injector, an accelerator-buncher, and a final transport system. Here only the accelerator portion of the driver is discussed.
Date: March 1, 1979
Creator: Faltens, A.; Hoyer, E.; Keefe, D. & Laslett, L.J.
Partner: UNT Libraries Government Documents Department