Showing papers on "Linear particle accelerator published in 1969"

Support structure for electron accelerator with deflecting means and target and cooperating patient support

Abstract: Improved linear accelerator apparatus for directing ionizing radiation on an object is realized by utilization of a horizontal axis of rotation about which the linear accelerator axis rotates while the accelerator axis maintains a horizontal spatial orientation at different circumferential points of rotation in conjunction with beam deflection means disposed at the downstream end portion of the accelerator which produce beam deflection along an axis different than the accelerator axis and preferably substantially 90* with respect thereto.

The Astron Linear Accelerator

Abstract: One of the primary requirements of the Astron controlled thermonuclear reactor experiment is an intense beam of relativistic electrons. An accelerator to produce such a beam with currents of the order of several hundred amperes has been in operation at the Lawrence Radiation Laboratory, Livermore, for several years. The accelerator operates on the principle of magnetic induction as applied to a linear accelerator. The original accelerator has been redesigned and rebuilt in order to increase the output beam current, to increase the beam energy, and to improve the quality of the output beam. Given in Table I is a comparison between the original machine and the design parameters for the new machine.

Performance of 140 MeV High Curret Short Pulse Linac at ORNL

Abstract: High current results of a 140-MeV electron traveling wave L-band linear accelerator are discussed. The 150-kV gridded gun injector has demonstrated pulse currents in excess of 30 A and pulse widths as narrow as 2.3 nsec at 1000 Hz. The accelerator wave guide sections are of nonuniform impedance design 4.3 m each and are driven by 24 mW, 67.5 kW L-band klystrons. Uniform solenoidal focusing is employed over the accelerating sections and quadrupole focusing is employed in beam transport. Short pulse current exceeding 16 A has been observed at the target position within an area of less than 4 Cm2.

Resonantly Coupled Standing Wave Accelerator Structures for Electron and Proton Linac Applications

Abstract: Standing wave accelerator tanks which utilize non-excited resonant elements for field stabilization have become standard in proton linac designs during the last few years. A general description of resonant coupling, with special emphasis on the energy propagation characteristics of resonantly coupled systems is given. Extension of resonant coupling to the coupling of short 0 or ? mode like sections is briefly discussed. The transient response of two resonantly coupled linac tanks, a post coupled drift tube linac and a side coupled linac tank are compared to conventional 0 or ? mode tank responses. Finally, a brief description of applications of resonantly coupled linac tanks to electron and proton linacs under construction in the U.S. is given.

A New Structure for Heavy-Ions Linacs

Abstract: This structure uses an essentially T.E. field instead of a T.M. one like in an Alvarez linear accelerator. The drift tubes are alternately connected to conducting plates fastened to the waveguide, so that the device operates on a ? mode. The shunt impedance is roughly proportional to s 1/2, so that this structure is convenient for injectors or heavy ions accelerators. This shunt impedance is higher than for an Alvarez structure for energies lower than about 20 MeV/nucleon in the case of a small diameter of drift-tubes (grid focusing), and lower than a few MeV/nucleon in the case of larger diameters (strong focusing). The wavelengths to be used are longer than in an Alvarez, so that the defocusing forces are weaker and focusing is easier. For a given acceleration, such a machine, using a ? mode, can be about twice as short as an Alvarez. A model accelerating deutons from 40 keV to 350 keV has been built and operates properly.

The 4-MeV Separated-Orbit Cyclotron

Abstract: The Separated-Orbit Cyclotron Experiment (SOCE) will extend and complement earlier theoretical and experimental studies and will provide a unique facility for the evaluation of an operating SOC system The six-sector, fourturn accelerator will provide maximum energies of 4 MeV for protons and deuterons and 8 MeV for 3He++ and 4He++ ions The output energy is variable over a 2:1 range by adjustment of the magnetic field and acceleration of the ions at the appropriate harmonic of the ion frequency Ions are injected into the SOC at one quarter the final energy The injection system consists of a duoplasmatron ion source, a 500-kV dc accelerator, and a three-cavity linear accelerator Proton currents in the 10-to 20-mA range are predicted The principal characteristics of the accelerator are given in Table I All of the major components have been fabricated and delivered on site except the injector's linac cavities, which are expected shortly The photograph in Fig 1 shows the accelerator as seen from the control area on a mezzanine about 40 feet away The SOC sector magnets and rf cavities are in the approximate location, with the dc injector components in the background The tops of the magnet yokes have been temporarily removed to permit completion of pole tip alignment An rf power amplifier will be mounted on the outer wall of each cavity One of the PA units can be seen in the background (Fig 1) on a test stand with a water-cooled dummy load

Report on the Performance of the Superconducting Injector for the Stanford Linear Accelerator

Abstract: This report describes some recent experiments performed with a prototype of the injector section eventually to be used in conjunction with the superconducting linear accelerator at Stanford University.

Feasibility Study of a Two-Mile Superconducting Linac

Abstract: Assuming that investigations now underway will result in superconducting accelerator structures capable of withstanding gradients of 33 MeV/m, a feasibility study of a two-mile 100 GeV superconducting electron linac with 6% duty cycle has been made at frequencies of 1428 and 2856 MHz. Tentative machine parameters and the preliminary design of components and systems have been examined. These studies are based upon a traveling-wave accelerator structure with RF feedback in each 20-ft section.

Study on Interdigital H-Type Structure for Heavy-Ion Linear Accelerator

Abstract: Due to the very low heavy-ion velocity at injection, the frequency must also be kept low enough and it turns out that Alvarez and twin-line structures become inefficient. Experimental works were carried out at Lyon on a new type of structures well suited for low velocity range, namely the interdigital H-type structure. The dimensions of this type of structure as well as their electrical characteristics proveto be very attractive at low frequency; furthermore, due to the particular field pattern in these resonators, radial focusing of the beam appears to be possible with magnetic quadrupoles at energy as low as 50-60 keV/nucleon and frequency in the range of 20-30 MHz. Such a field pattern also gives good acceptances for the whole cavity. This paper presents our last results, discusses various problems and gives the main parameters of Lyon's 10 MeV/nucleon heavy-ionliner accelerator project.

Progress in Proton Linear Accelerators

Abstract: Two new proton linacs have recently come into operation; both are \"conventional\" drift tube types (they do not incorporate any of the recently devised field stabilization techniques). First is the 100 MeV linac injector for the 76 GeV synchrotron at Serpukhov in the USSR. This linac2p3 has been operating well for a year and a half and has achieved a peak current in excess of 100 mA. The other is the new 20 MeV injector for Saturne at Saclay. This linac,4 which incorporates a pressurized Cockcroft-Walton preaccelerator, has been operating for almost one year and produces a beam close to its design current of 20 mA. A number of refinements have been added to several existing linacs. In particular, at BNL the 50 MeV linac has been fitted with a high intensity duoplasmatron source and a high gradient column as well a3 a multiport RF system, and 'these modifications 30 far have raised the output current from 30 mA in 1.1 cm-mrad to 55 mA in 1.4 cm-mrad, an increase of about 50% in brightness.

Fast Beam Choppers for the Electron-Ring Accelerator

Abstract: Two beam choppers were constructed which produce an approximately square, 20-ns pulse of 3+-MeV electrons out of the best portion of the 300-ns Astron beam or an 8-?s microwave electron linac beam for injection into the electronring accelerator (ERA) compressor. The choppers are impedance-matched traveling-wave devices which deflect the beam with equal strength electric and magnetic forces, and are powered with either three-electrode spark gaps or thyratrons and a 20-ns pulse line. The electron beam is biased out of the beam-transport system with a dc magnetic field, and switched into it with the chopper.

The Injector Complex for the LAMPF Accelerator

Abstract: The present planning and design goals for the LAMPF injector complex include a high-intensity H+ beam, an H- beam, and polarized H+ and H- beams. Since simultaneous acceleration of H+ and H- beams will be attempted by the LAMPF accelerator, a dual beam-transport system for blending these beams into a common channel will be necessary in the injector area. Provision also is made for injecting either H+ or H- polarized beams into the system. A high-quality beam of protons (? cm-mrad emittance and 26 mA) has been produced by a von Ardenne duoplasmatron and a Pierce extraction accelerating column. Problems of simultaneous bunching and matching of H+ and H- beams of different intensities have been studied. The entire injector complex is under computer control and should provide reasonably sophisticated pulse programming flexibility.

Improvements in or relating to Accelerators for Charged Particles

Abstract: 1,165,181. Partial accelerators. SCIENCE RESEARCH COUNCIL. 6 Jan., 1967 [14 Jan., 1966], No. 1976/66. Heading H1D. In a separated orbit cyclotron comprising an alternating series of electromagnets 1, Fig. 2, and radio-frequency excited cavities 2 disposed in a closed ring, the cavities are excited by one or more pulsed electron beams 5 circulating outside the spiral path followed by the accelerated beam 3 of e.g. protons. The widths of the portions 6 of the cavities through which the electron beams pass are the same but to allow for decrease in beam velocity the relative locations in azimuth of the portions vary and the beams are guided by magnets 7. The beams are coupled to the cavities at zero phase angle relative to the electric field and cavities 8 operated at a high harmonic of the frequency of the cavities 2 are provided to reduce energy dispersion. The electron beams are introduced with relativistic velocities and are generated in apparatus comprising a plurality of electron guns 10, Fig. 3, with modulating grids 15 and a plurality of D.C. linear accelerators 12. The high voltages applied to the accelerator electrodes are developed by a high-voltage generator 17 as described in Specification 1,165,182. The voltages developed across capacitors are applied between pairs of accelerator electrodes common to all the accelerators. Quadrupole focusing magnets 31 are provided between some of the accelerator electrodes. A proton beam may be accelerated successively in a linear accelerator and three separate cyclotrons of increasing energy. In the lower energy cyclotrons the electron beams are circulated at half the synchronous radius and the cavities are spaced such that the proton beam is accelerated once every two cycles of the radio-frequency.

Vacuum System for High-Radiation Environment at the RPI Linac Laboratory

Abstract: Vacuum system components on the RPI Linear Accelerator must operate in radiation fields averaging 5×105 rad/sec. Experience gained since the start of operations eight years ago indicates the special problems of constructing, maintaining, and modifying systems for high-radiation environments.

Field Distribution in a Centrally Loaded Circular Cylindrical Cavity

Abstract: To accelerate protons in an Alvarez type linear accelerator or electrons in velocity modulated tubes, the cavity must be excited in the dominant TM010 mode. For proper understanding of beam dynamics and for purposes of design, the r.f. fields must be computed accurately for any specified dimensions of the drift space. In this paper the exact numerical solution for the fields in a drift tube loaded linear accelerator cavity with a beam guiding hole is presented. The eigenvalues, field distribution, transit time factor and the shunt impedance are formulated everywhere by boundary value techniques in the same manner as proposed by Bolle and Gluckstern in the absence of the beam guiding hole. The numerical results are obtained with the aid of a digital computer and are established by an excellent agreement with an experiment based on perturbation techniques.

Proposed Modifications of the Berkeley Hilac

Abstract: Improvements are planned for the Berkeley Heavy Ion Linear Accelerator which will make possible the acceleration of all elements from hydrogen to uranium to 7.5 MeV/nucleon. The improved system will consist of a 2.7 MV dc injector, a new 11 meter-long prestripper linac and the existing 27 meter long poststripper linac which will be extended to 37 meters. Baffles in the latter portion of this cavity will separate it into individually excited segments to provide completely variable energy from 3 to 7.5 MeV/nucleon. To provide the lighter heavy ion beams, at energies acceptable for biological research and medical therapy, a 25 meter diameter rapid cycling alternating gradient synchrotron is proposed. With this machine fully stripped ions from the Hilac with M?20 can be accelerated to energies up to 500 MeV/nucleon. Details of the synchrotron design will closely follow those developed for the Omnitron and a prototype of the Omnitron accelerating resonator will be used.