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TRACE 3-D documentation

Description: TRACE 3-D is an interactive beam-dynamics program that calculates the envelopes of a bunched beam, including linear space-charge forces, through a user-defined transport system. TRACE 3-D provides an immediate graphics display of the envelopes and the phase-space ellipses and allows nine types of beam-matching options. This report describes the beam-dynamics calculations and gives detailed instruction for using the code. Several examples are described in detail.
Date: August 1, 1987
Creator: Crandall, K.R.
Partner: UNT Libraries Government Documents Department

Documentation for TRACE: an interactive beam-transport code

Description: TRACE is an interactive, first-order, beam-dynamics computer program. TRACE includes space-charge forces and mathematical models for a number of beamline elements not commonly found in beam-transport codes, such as permanent-magnet quadrupoles, rf quadrupoles, rf gaps, accelerator columns, and accelerator tanks. TRACE provides an immediate graphic display of calculative results, has a powerful and easy-to-use command procedure, includes eight different types of beam-matching or -fitting capabilities, and contains its own internal HELP package. This report describes the models and equations used for each of the transport elements, the fitting procedures, and the space-charge/emittance calculations, and provides detailed instruction for using the code.
Date: January 1, 1985
Creator: Crandall, K.R. & Rusthoi, D.P.
Partner: UNT Libraries Government Documents Department

RFQ pole-tip construction

Description: The success of the radio-frequency quadrupole (RFQ) proof-of-principle (POP) tests conducted in 1980 at Los Alamos have essentially guaranteed that the RFQ linac will be used in many accelerator projects soon. Several RFQs are already under construction at Los Alamos, and we expect to be designing and machining the vanes for several RFQs to be built at other installations. The technique for machining the vanes for the POP RFQ was developed by Williams and Potter. While retaining their basic approach, we have modified their technique for generating the data required by the milling machine from the parameters defining the vane shapes. The objective of this exercise has been to develop a generalized fabrication procedure that could be used in commercial machine shops.
Date: January 1, 1981
Creator: Crandall, K.R. & Stovall, J.E.
Partner: UNT Libraries Government Documents Department

PARMTEQ (Phase And Radial Motion in Transverse Electric Quadrupole linacs): A beam dynamics code for the RFQ (radio-frequency quadrupole)

Description: The PARMTEQ code is used for generating the complete cell design of a radio-frequency quadrupole linear accelerator and for multiparticle simulation of the beam dynamics. We present a review of the code, with an emphasis on the physics used to describe the particle motion and the cell generation. 9 refs., 1 fig.
Date: January 1, 1987
Creator: Crandall, K.R. & Wangler, T.P.
Partner: UNT Libraries Government Documents Department

RFQ (radio-frequency quadrupole) accelerators for heating thermonuclear plasmas

Description: The radio-frequency quadrupole (RFQ) accelerator has been developed to generate high-current ion beams for a wide variety of applications. It has also been suggested that this type of accelerator could be used to produce megawatt ion beams to heat thermonuclear reactor plasmas. For a tokamak reactor, an RFQ accelerator can be designed to provide negative deuterium ions that are neutralized before injection through the tokamak magentic field. Also, it may be possible to use singly charged, positive, heavier ions that trasverse the magnetic field with minimal deflection and then become multiply ionized upon striking the tokamak plasma. We present preliminary RFQ beam-dynamics designs for both deuterium and oxygen ions.
Date: January 1, 1987
Creator: Stokes, R.H.; Wangler, T.P. & Crandall, K.R.
Partner: UNT Libraries Government Documents Department

Performance characteristics of a 425 MHz RFQ linac

Description: A radio-frequency quadrupole (RFQ) focused proton linac has been developed and successfully tested at the Los Alamos Scientific Laboratory (LASL) for the purpose of evaluating its performance and applicability as a low-beta accelerator. The geometry of the structure was designed to accept a 100-keV beam, focus, bunch, and accelerate it to 640 keV in 1.1 m with a high-capture efficiency and minimum emittance growth. The accelerator test facility includes an injector, low-energy transport section for transverse matching, and a high-energy transport section for analysis of the beam properties. The accelerator cavity is exited through a manifold powered by a 450-MHz klystron. Diagnostic instrumentation was prepared to facilitate operation of the accelerator and to analyze its performance. Measurements of the beam properties are presented and compared with the expected properties resulting from numerical calculations of the beam dynamics.
Date: January 1, 1980
Creator: Stovall, J.E.; Crandall, K.R. & Hamm, R.W.
Partner: UNT Libraries Government Documents Department

Accelerator column models for low-current beams

Description: This paper describes three analytic approaches used to model electrostatic accelerator columns in beam-transport codes for low-current beams and compares the results of each approach with the results obtained by numerically calculating the electric field based on charge distribution on equipotential surfaces. The three analytic approaches described are (1) a cubic energy-gain approximation, (2) a cubic longitudinal electric-field approximation, and (3) the aperture equation. The first two approaches calculate impulse approximations at the apertures, whereas the third is an integration of particle trajectories through the column filed. The conditions under which the solutions tend to break down are discussed. 4 refs., 8 figs.
Date: January 1, 1985
Creator: Rusthoi, D.P.; Allison, P. & Crandall, K.R.
Partner: UNT Libraries Government Documents Department

Radio-frequency quadrupole vane-tip geometries

Description: Radio-frequency quadrupole (RFQ) linacs are becoming widely accepted in the accelerator community. They have the remarkable capability of simultaneously bunching low-energy ion beams and accelerating them to energies at which conventional accelerators can be used, accomplishing this with high-transmission efficiencies and low-emittance growths. The electric fields, used for radial focusing, bunching, and accelerating, are determined by the geometry of the vane tips. The choice of the best vane-tip geometry depends on considerations such as the peak surface electric field, per cent of higher multipole components, and ease of machining. We review the vane-tip geometry based on the ideal two-term potential function and briefly describe a method for calculating the electric field components in an RFQ cell with arbitrary vane-tip geometry. We describe five basic geometries and use the prototype RFQ design for the Fusion Materials Irradiation Test (FMIT) accelerator as an example to compare the characteristics of the various geometries.
Date: January 1, 1983
Creator: Crandall, K.R.; Mills, R.S. & Wangler, T.P.
Partner: UNT Libraries Government Documents Department

Radio-frequency quadrupole: general properties and specific applications

Description: The radio-frequency quadrupole (RFQ) linac structure is being developed for the acceleration of low-velocity ions. Recent experimental tests have confirmed its expected performance and have led to an increased interest in a wide range of possible applications. The general properties of RFQ accelerators are reviewed and beam dynamics simulation results are presented for their use in a variety of accelerating systems. These include the low-beta sections of the Fusion Materials Irradiation Test Accelerator, a 200-MHz proton linear accelerator, and a xenon accelerator for heavy ion fusion.
Date: January 1, 1980
Creator: Stokes, R.H.; Crandall, K.R. & Hamm, R.W.
Partner: UNT Libraries Government Documents Department

rf quadrupole linac: a new low-energy accelerator

Description: A new concept in low-energy particle accelerators, the radio-frequency quadrupole (RFQ) linac, is currently being developed at the Los Alamos National Scientific Laboratory. In this new linear accelerating structure both the focusing and accelerating forces are produced by the rf fields. It can accept a high-current, low-velocity dc ion beam and bunch it with a high capture efficiency. The performance of this structure as a low-energy linear accelerator has been verified with the successful construction of a proton RFQ linac. This test structure has accelerated 38 mA of protons from 100 keV to 640 keV in 1.1 meters with a capture efficiency greater than 80%. In this paper a general description of the RFQ linac and an outline of the basic RFQ linac design procedure are presented in addition to the experimental results from the test accelerator. Finally, several applications of this new accelerator are discussed.
Date: January 1, 1980
Creator: Hamm, R.W.; Crandall, K.R. & Fuller, C.W.
Partner: UNT Libraries Government Documents Department

RF quadrupole beam dynamics design studies

Description: The radio-frequency quadrupole (RFQ) linear accelerator structure is expected to permit considerable flexibility in achieving linac design objectives at low velocities. Calculational studies show that the RFQ can accept a high-current, low-velocity, dc beam, bunch it with high efficiency, and accelerate it to a velocity suitable for injection into a drift-tube linac. Although it is relatively easy to generate a satisfactory design for an RFQ linac for low beam currents, the space-charge effects produced by high currents dominate the design criteria. Methods have been developed to generate solutions that make suitable compromises between the effects of emittance growth, transmission efficiency, and overall structure length. Results are given for a test RFQ linac operating at 425 MHz.
Date: January 1, 1979
Creator: Crandall, K.R.; Stokes, R.H. & Wangler, T.P.
Partner: UNT Libraries Government Documents Department

RFQ development at Los Alamos

Description: The basic principles of the radio-frequency quadrupole (RFQ) linac are reviewed and a summary of past and present Los Alamos work is presented. Some beam-dynamics effects, important for RFQ design, are discussed. A design example is shown for xenon and a brief discussion of low-frequency RFQ structures is given.
Date: January 1, 1982
Creator: Wangler, T.P.; Crandall, K.R. & Stokes, R.H.
Partner: UNT Libraries Government Documents Department

Emittance growth in intense beams

Description: Recent progress in the study of high-current, low-emittance, charged-particle beams may have a significant influence in the design of future linear accelerators and beam-transport systems for higher brightness applications. Three space-charge-induced rms-emittance-growth mechanisms are now well established: (1) charge-density redistribution, (2) kinetic-energy exchange toward equipartitioning, and (3) coherent instabilities driven by periodic focusing systems. We report the results from a numerical simulation study of emittance in a high-current radio-frequency quadrupole (RFQ) linear accelerator, and present a new semiempirical equation for the observed emittance growth, which agrees well with the emittance growth predicted from numerical simulation codes.
Date: March 1, 1987
Creator: Wangler, T.P.; Mills, R.S. & Crandall, K.R.
Partner: UNT Libraries Government Documents Department

Particle-beam accelerators for radiotherapy and radioisotopes

Description: The philosophy used in developing the new PIGMI technology was that the parameters chosen for physics research machines are not necessarily the right ones for a dedicated therapy or radioisotope machine. In particular, the beam current and energy can be optimized, and the design should emphasize minimum size, simplicity and reliability of operation, and economy in capital and operating costs. A major part of achieving these goals lay in raising the operating frequency and voltage gradient of the accelerator, which shrinks the diameter and length of the components. Several other technical innovations resulted in major system improvements. One of these is a radically new type of accelerator structure named the radio-frequency quadrupole (RFQ) accelerator. This allowed us to eliminate the large, complicated ion source used in previous ion accelerators, and to achieve a very high quality accelerated beam. Also, by using advanced permanent magnet materials to make the focusing elements, the system becomes much simpler. Other improvements have been made in all of the accelerator components and in the methods for operating them. These will be described, and design and costing information examples given for several possible therapy and radioisotope production machines.
Date: January 1, 1981
Creator: Boyd, T.J.; Crandall, K.R. & Hamm, R.W.
Partner: UNT Libraries Government Documents Department

PIGMI linear-accelerator technology

Description: A new linear-accelerator technology has been developed that makes pi-meson (pion) generation possible for cancer therapy in the setting of a major hospital center. This technology uses several new major inventions in particle accelerator science-such as a new accelerator system called the radio-frequency quadrupole (RFQ), and permanent-magnet drift-tube focusing-to substantially reduce the size, cost, and complexity of a meson factory for this use. This paper describes this technology, discusses other possible uses for these new developments, and finally discusses possible costs for such installations.
Date: January 1, 1981
Creator: Boyd, T.J.; Crandall, K.R. & Hamm, R.W.
Partner: UNT Libraries Government Documents Department

Designing self-matching linacs

Description: The present trend in ion-linac design is to begin with a radio-frequency quadrupole (RFQ) linac followed by one or more drift-tube linac (DTL) tanks in which permanent-magnet quadrupoles are used for transverse focusing. The lack of adjustable elements (knobs) strongly suggests that one should seek linac designs with intertank matching solutions that are insensitive to beam currents and emittances, which can be accomplished if there are no sharp discontinuities in the focusing properties along the entire linac. Guidelines are presented for linac design and describe techniques for longitudinal as well as transverse matching between tanks. For a wide range of beam currents and emittances, a beam matched at the entrance to the RFQ should remain well matched throughout the entire linac.
Date: January 1, 1984
Creator: Mills, R.S.; Crandall, K.R. & Farrell, J.A.
Partner: UNT Libraries Government Documents Department

Radio-frequency quadrupole: a new linear accelerator

Description: In many Laboratories, great emphasis now is placed on the development of linear accelerators with very large ion currents. To achieve this goal, a primary concern must be the low-velocity part of the accelerator, where the current limit is determined and where most of the emittance growth occurs. The use of magnetic focusing, the conflicting requirements in the choice of linac frequency, and the limitations of high-voltage dc injectors, have tended to produce low-velocity designs that limit overall performance. The radio-frequency quadrupole (RFQ) linear accelerator, invented in the Soviet Union and developed at Los Alamos, offers an attractive solution to many of these low-velocity problems. In the RFQ, the use of RF electric fields for radial focusing, combined with special programming of the bunching, allows high-current dc beams to be captured and accelerated with only small beam loss and low radial emittance growth. Advantages of the RFQ linac include a low injection energy (20 to 50 keV for protons) and a final energy high enough so the beam can be further accelerated with high efficiency in a Wideroee or Alvarez linac. These properties have been confirmed at Los Alamos in a highly successful experimental test performed during the past year. The success of this test and the advances in RFQ design procedures have led to the adoption of this linac for a wide range of applications. The beam-dynamics parameters of three RFQ systems are described. These are the final design for the protytype test of the Fusion Materials Irradiation Test (FMIT) accelerator, the final design for the prototype test of the Pion Generator for Medical Irradiations (PIGMI), and an improved low-velocity linac for heavy ion fusion.
Date: January 1, 1981
Creator: Stokes, R.H.; Wangler, T.P. & Crandall, K.R.
Partner: UNT Libraries Government Documents Department

Further improvements on TRACE 3-D

Description: TRACE 3-D, an interactive beam-dynamics program that calculates the envelopes of a bunched beam (including linear space-charge forces) through a user-defined transport system, has undergone several upgrades in physics, coding, and capabilities. Recent modifications include centroid tracking (and misalignment capabilities) and an improved beam description that allows study of some nonlinear effects such as wakefields. The Fortran code has been made portable and runs on numerous platforms. It can be used with a variety of graphics packages. The additional beamline elements, new commands, expanded fitting capabilities, improved beam description, and coding modifications have extended TRACE 3-D`s usefulness and applicability to the accelerator community. These changes are documented in the third edition of TRACE 3-D Documentation.
Date: August 1, 1997
Creator: Rusthoi, D.P.; Lysenko, W.P. & Crandall, K.R.
Partner: UNT Libraries Government Documents Department

Octopole correction of geometric aberrations for high-current heavy-ion fusion beams

Description: The success of heavy-ion fusion depends critically on the ability to focus heavy-ion beams to millimeter-size spots. Third-order geometric aberrations caused by fringe fields of the final focusing quadrupoles can significantly distort the focal spot size calculated by first-order theory. We present a method to calculate the locations and strengths of the octopoles that are needed to correct these aberrations. Calculation indicates that the strengths of the octopoles are substantially less than that of the final focusing quadrupoles. 9 refs., 1 fig.
Date: March 17, 1989
Creator: Ho, D.D.M.; Haber, I.; Crandall, K.R. & Brandon, S.T.
Partner: UNT Libraries Government Documents Department

Octupole focusing in transport and acceleration systems

Description: The radio-frequency quadrupole (RFQ) linac is capable of accelerating high-current, low-velocity ion beams. In accelerator systems comprising an RFQ and higher velocity accelerating structures, the current bottleneck still typically occurs within the RFQ. This limiting current is quite high in most cases, but linacs with even higher currents may be required in the future. We have begun a study of higher multipole systems to determine their capability for focusing and accelerating very high currents. We have chosen first to examine a radio-frequency octupole (RFO) transport system, and have developed a smooth-approximation analytical description that includes the conditions for input radial matching of a zero space-charge beam. Further, we have constructed a multiparticle beam-dynamics simulation program that accepts the low-current matched beam and gradually increases the beam current as it is transported. This results in a matched high-current beam, and the procedure can be used to determine the saturation-current limit of a periodic octupole system. As expected, at high currents the beam develops a hollow radial distribution that reduces the space-charge defocusing; initial results show that high currents can be transported. For acceleration, we have formulated the design parameters for a section of RFO linac, including the potential function, acceleration, and focusing efficiencies, and the geometry of the radially modulated pole tips.
Date: January 1, 1981
Creator: Crandall, K.R.; Pabst, M.; Stokes, R.H. & Wangler, T.P.
Partner: UNT Libraries Government Documents Department

Operating characteristics of a 2. 0-MeV RFQ

Description: A second radio-frequency quadrupole (RFQ) accelerator has been designed, constructed and operated at Los Alamos National Laboratory. The accelerator's design parameters represent a major extension from the original Los Alamos RFQ, with the new accelerator being 2.5 times as long, having three times the output energy, and with 2.5 times the current limit. The new accelerator's operating characteristics were studied for 3 months before disassembly to incorporate design mofidications. Results are discussed.
Date: January 1, 1983
Creator: Purser, F.O.; Wadlinger, E.A.; Sander, O.R.; Potter, J.M. & Crandall, K.R.
Partner: UNT Libraries Government Documents Department

Octupole focusing in transport and accelerator systems

Description: The radio-frequency quadrupole (RFQ) linac is capable of accelerating high-current, low-velocity ion beams. In accelerator systems comprising an RFQ and higher velocity accelerating structures, the current bottleneck still typically occurs within the RFQ. This limiting current is quite high in most cases, but linacs with even higher currents may be required in the future. We have begun a study of higher multipole systems to determine their capability or focusing and accelerating very high currents. We have chosen first to examine a radio-frequency octupole (RFQ) transport system, and have developed a smooth-approximation analytical description that includes the conditions for input radial matching of a zero space-charge beam. Further, we have constructed a multiparticle beam-dynamics simulation program that accepts the low-current matched beam and gradually increases the beam current as it is transported. This results in a matched high-current beam, and the procedure can be used to determine the saturation-current limit of a periodic octupole system. As expected, at high currents the beam develops a hollow radial distribution that reduces the space-charge defocusing; initial results show that high currents can be transported. For acceleration, we have formulated the design parameters for a section of RFQ linac, including the potential function, acceleration, and focusing efficiencies, and the geometry of the radially modulated pole tips.
Date: January 1, 1981
Creator: Crandall, K.R.; Pabst, M.; Stokes, R.H. & Wangler, T.P.
Partner: UNT Libraries Government Documents Department