Notification:
We are currently experiencing intermittent issues impacting performance. We apologize for the inconvenience.
By Topic

Particle Accelerator Conference, 1989. Accelerator Science and Technology., Proceedings of the 1989 IEEE

Date 20-23 March 1989

Filter Results

Displaying Results 1 - 25 of 659
  • A magnetically switched kicker for proton extraction

    Publication Year: 1989 , Page(s): 402 - 404 vol.1
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (259 KB)  

    The application of magnetic current amplification and switching techniques to the generation of precise high current pulses for switching magnets is described. The square loop characteristic of Metglas tape wound cores at high excitation levels provides excellent switching characteristics for microsecond pulses. The rugged and passive nature of this type of pulser makes it possible to locate the final stages of amplification at the load for maximum efficiency.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Description of new vacuum chamber correction concept

    Publication Year: 1989 , Page(s): 384 - 386 vol.1
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    For rapid cycled accelerators, eddy currents induced in vacuum chambers (VCs) are typically the dominant source of systematic and random field aberrations. Complex thin wall VCs are expensive and delicate where bakeout is required, as in the AGS Booster under construction. Thick wall VCs are rugged and economical but produce large eddy currents. A self-correction concept has been developed and tested which corrects automatically by transformer action, even for variable B cycles. Coils attached to the outside of the VC cancel eddy current aberrations over the entire 'good field' aperture. The correction coils follow the local contour of the VC, so large transverse VC movements are tolerated; both the aberrations and their corrections have the same displaced coordinates. Experimental results are presented for Booster correction coil designs demonstrating both self-correction and excitation by a separate power supply. Analytic results applicable to the Booster and other fast cycling accelerators are discussed. The eddy current field aberrations induced in a preproduction full-size VC inserted in an AGS Booster dipole have been successfully eliminated by the self-correction coils attached to its surface. The voltage induced in a two-turns-per-pole 'back leg' winding is sufficient to supply the necessary current through the correction winding.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Proceedings of the 1989 IEEE Particle Accelerator Conference. Accelerator Science and Technology (Cat. No.89CH2669-0)

    Publication Year: 1989
    Save to Project icon | Request Permissions | PDF file iconPDF (2417 KB)  
    Freely Available from IEEE
  • Drift tubes for a focusing channel of ion linear accelerator

    Publication Year: 1989 , Page(s): 1073 - 1075 vol.2
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (453 KB)  

    An open-to-vacuum drift tube with nonorganic (i.e. rare-earth) magnetic quadrupole lens elements has been developed. This design almost completely eliminates local deteriorations of vacuum quality leading to multipactor RF discharges. Drift tubes of this type have been manufactured and installed in the 56-MeV proton linac. The resonator would provide an output energy of 10 MeV. Descriptions are given of the permanent magnetic lenses and the mechanical design of the drift tubes. The magnetic performance is summarized.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Relativistic klystrons

    Publication Year: 1989 , Page(s): 1123 - 1127 vol.2
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (505 KB)  

    Experimental work is underway to investigate the feasibility of using relativistic klystrons as a power source for future high-gradient accelerators. The aim is to develop a high-power (500-MW) short-wavelength (2.6-cm) relativistic klystron with beam kinetic energy greater than 1 MeV. Two different relativistic klystron configurations have been built and tested: a high-gain multicavity klystron at 11.4 GHz and a low-gain two-cavity subharmonic buncher driven at 5.7 GHz. In both configurations power is extracted at 11.4 GHz. In order to understand the basic physics issues involved in extracting RF from a high power beam, both a single resonant cavity and a multicell traveling-wave structure were used for energy extraction. A previously reported problem of high-power RF pulse shortening was overcome, and peak RF power levels of 170 MW have been achieved with the RF pulse of the same duration as the beam current pulse.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new design of the SSC boosters

    Publication Year: 1989 , Page(s): 1331 - 1333 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (270 KB)  

    A new design for the lattices of the SSC's (Superconducting Super Collider's) three injectors is presented. The complex is matched so that the SSC filling factor is 94%, and is designed so that there is no transition crossing at any point. The dispersion function is small overall and vanishes in the straight sections. Tracking simulations which include the effect of the space-charge force, sextupoles, synchrotron oscillations, and the expected random and systematic dipole magnet errors indicate that the CDR magnet design allows adequate dynamic aperture for all three boosters and that the space-charge force in the LEB has no significant detrimental effect provided the LEB is tuned properly.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A noniterative method for calculating beam position from induced electric signals

    Publication Year: 1989 , Page(s): 1519 - 1522 vol.3
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (290 KB)  

    The pickup electrodes (PUEs) in the NSLS (National Synchrotron Light Source) storage rings are of the four-button type. Near the center of the PUE, the beam position can be well approximated with a linear function of the sum and the difference signals induced on these electrodes by the bunched beam. The nonlinear response of the PUEs further from the center was measured. An algorithm to compensate for this effect was developed.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The CCVV high-current megavolt-range DC accelerator

    Publication Year: 1989 , Page(s): 1117 - 1119 vol.2
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    The authors describe a constant-current variable-voltage (CCVV) accelerator, intended to operate in the megaelectronvolt energy range but tunable down to a few percent of magnetoelectronvolt without loss of beam current. They present experimental results from a 200-keV single-beam prototype system designed to accelerate up to 0.2 A of H+ or H- or the equivalent current of heavier ions. The beam is accelerated by a series of stackable 100-keV modules, the number depending on the maximum beam energy required. The authors discuss a proposed 1-MeV accelerator and a conceptual design for a multiaperture system accelerating 10 A or D- ions to 1-2 MeV for current drive in a fusion reactor. The use of electrostatic quadrupole focusing allows a conservative design with reduced risk of voltage breakdown and makes it possible to maintain high currents while varying the beam energy. These features are useful for fusion reactor startup and for industrial applications, such as semiconductor processing and surface hardening View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Advanced Accelerator Test Facility (AATF) upgrade plan

    Publication Year: 1989 , Page(s): 612 - 614 vol.1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    The principles of wakefield acceleration employing structures (cavity, dielectric) and plasmas as wakefield devices have been successfully demonstrated using the AATF at Argonne National Laboratory. Due to the limited driver electron pulse intensity and relatively long pulse length, only modest accelerating gradients were observed. In order to study the wakefield effects in much greater detail and demonstrate the feasibility of a wakefield accelerator for high energy physics, construction of a laser photocathode injector on the existing 20-MeV Chem-Linac to produce very intense and short electron pulses is being considered. The laser photocathode design and computer simulation of its performance are described. The experiments performed using the upgraded facility are discussed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Advanced Light Source (ALS) beam position monitor

    Publication Year: 1989 , Page(s): 1507 - 1509 vol.3
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    The requirements, design, and performance of the ALS BPM (beam position monitor) system are discussed. Considerable effort has gone into the storage-ring BPM system design because very fast and accurate measurements are needed. The speed and accuracy requirements in the electronics are met with parallel processing and error-correction techniques. A tuned receiver is provided for every beam position pickup, and for every array of four pickups there is a microprocessor controlling the measurement and recording data. To be useful during storage-ring commissioning, injection studies, and at other times when instant response is required, the BPM system must respond to a single turn of beam and also be able to store data from many turns. This is especially important with a low injection rate. The required bandwidth in this case is about 2 MHz. Accuracy and resolution of 0.5 mm are adequate for these high-speed measurements View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Boeing 120 MeV RF linac injector design and accelerator performance comparison with PARMELA

    Publication Year: 1989 , Page(s): 657 - 659 vol.1
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    The injector for the Boeing 120-MeV L-band RF linac was designed to produce 400-A peak current electron beam pulses with minimal emittance growth. PARMELA, a mostly three-dimensional matrix ray trace code with a two-dimensional space charge model, was used to determine the optimum setting of the injector elements for tuning purposes. The injector model predictions were used to tune the injector with very good agreement between the model and the experiment. Beam dynamics modeling from the gun through the sixth accelerating section was done with PARMELA, using experimental settings for the beamline elements. Excellent agreement between PARMELA predictions and experimental results was observed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determination of the beam width in a stellatron accelerator

    Publication Year: 1989 , Page(s): 615 - 617 vol.1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    The UCI (University of California Univ., Irvine) stellatron is a strong-focusing, high-current betatron that accelerates a 1-kA electron beam. To measure the minor dimension of the beam, targets were inserted at different radii from the outer sides of the torus. The beam was swept outward by applying a pulse vertical magnetic field. The time dependence of the X-ray emission from the target was analyzed to determine the expansion velocity and the density distribution of the beam. 50% and 90% of the electrons were found within 4-mm and 7-mm radii, respectively, at 5 MeV View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Mechanical design of SXLS radio-frequency cavity

    Publication Year: 1989 , Page(s): 263 - 265 vol.1
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    The mechanical design of an all-copper RF cavity for the Superconducting X-ray Lithography Source (SXLS) is described. The design has been optimized for space and functional requirements by analytical studies using Superfish and ANSYS computer programs. Resonance frequency variation due to thermal deformations is minimized by water channels machined onto the main structure. The effects of pressure deformations, residual thermal deflections, and mechanical tolerances are compensated by adjusting the gap size through step machining of the drift tube nose which is separable from the main body. An ultrahigh vacuum is achieved by pumping through conical vacuum port with a 220-l/s ion pump. The design provides for a tuner to compensate for the frequency drift under thermal and reactive beam loads during the operation, and antennas for the suppression of higher-order modes. Multipactoring effects are controlled by sputtering the cavity with titanium and backfilling it with dry nitrogen View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The beam profile measurement system at the Bates linac

    Publication Year: 1989 , Page(s): 1523 - 1525 vol.3
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    A linac beam profile measurement system using wire scanners has been implemented at the Bates Linear Accelerator Center. Obtaining an optimum linac focussing solution is facilitated by the system. A nearly noninvasive beam size measurement is made of the two beams which are accelerated simultaneously in the recirculating linac. The wire scanner's mechanical accuracy is near one mil. Beam size measurements are reproducible to a few mils View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Precision measurements of the SLC reference magnets

    Publication Year: 1989 , Page(s): 1547 - 1549 vol.3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    Two spectrometers, one on each extraction line of the SLC (Stanford Linear Collider), have been installed to momentum analyze each SLC beam pulse and determine the electron and positron beam energies. A method of determining and monitoring the absolute magnetic field strength for these dipoles has been developed. A total error on the magnetic field integral of δ∫Bdl/∫Bdl=1×10-4 has been achieved. The field integral can be monitored continuously during SLC beam operation using radiation-hardened equipment. The laboratory field mapping techniques and the field monitoring methods are described View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Brief review of the development of electrostatic accelerators and continuing work at Strasbourg

    Publication Year: 1989 , Page(s): 1103 - 1106 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    After a historical review of the development of electrostatic accelerators, work being done at the Centre de Recherches Nucleaires, Strasbourg, France, is described. Particular interest is placed on the 35-MV Vivitron accelerator, which uses a mixture of old and new concepts. New in the vivitron is the method of terminal and column support, the configuration of potential-defining electrodes, and the choice of insulating materials in the voltage generator. At the present time the activities of the Vivitron group are concerned mainly with the construction of the accelerator and with the different technological aspects of this work. Attention has also been given to more fundamental problems such as those concerned with the particle beam View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Plasma wakefield accelerator experiments in KEK

    Publication Year: 1989 , Page(s): 618 - 620 vol.1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    A plasma wakefield experiment is discussed. It uses an existing linac with a relativistic beam, which is separated into several bunches by the RF field. Specifically, use is made of the positron linac, the injector of the Photon Factory (PF), and the TRISTAN Accumulation Ring of the National Laboratory for High Energy Physics (KEK). The preceding bunches generate the wakefield in a plasma to accelerate or decelerate the following bunches. The linear theory predicts an accelerating gradient of approximately 80 MeV/m for this experiment View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparison of analytical and computational estimates of reduction in linear aperture in the presence of sextupole field

    Publication Year: 1989 , Page(s): 897 - 899 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    For an easy comparison of the expected improvement in the linear aperture when magnets are sorted according to various schemes, it is desirable to have a figure of merit which can be evaluated without time-consuming tracking calculations. Such a figure of merits is proposed in terms of the sextupole distortion functions introduced by T. Collins (9184). A test lattice composed of 512 dipoles with a random sextupole field component is used to calculate the figure of merit, and the indicated improvement in the linear aperture is compared with the results from numerical tracking. Two definitions for the linear aperture are used, one by the SSC-CDG (smear=6.4%) and the other by CERN SPS (Super Proton Synchrotron) (smear=1.75%) View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Active interlock for storage ring insertion devices

    Publication Year: 1989 , Page(s): 266 - 267 vol.1
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    The insertion devices in the NSLS (National Synchrotron Light Source) X-ray ring produce such intense photon beams that passive measures alone are not adequate to protect the vacuum chamber. An active interlock is used to prevent thermal damage from improperly steered electron beams. The interlock system measures the position of the electron beam on both sides of the insertion devices using pickup electrodes and interrupts the RF if the beam moves outside a safe window. The interlock features redundant circuitry as well as an automatic testing procedure View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Suppression of longitudinal coupled-bunch instability in UVSOR

    Publication Year: 1989 , Page(s): 918 - 920 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    The UVSOR is a 750-MeV electron storage ring used solely for vacuum ultraviolet synchrotron radiation research in molecular science and related fields. A longitudinal coupled-bunch instability excited by higher-order-mode resonances of the RF cavity was observed when routine operation of the ring was started. Two methods of curing the instability were tried, i.e. a feedback method and a decoupling method. The former system consists of 16 independent feedback loops; each of them corrects the energy deviation of one of 16 bunches. Although the system can suppress the instability, critical adjustment is required, i.e. the feedback loops have to be finely adjusting according to parameters such as the electron energy, the beam current, and the RF acceleration voltage. The latter system spreads synchrotron frequencies of individual bunches by the modulation of the effective acceleration voltage to decouple these synchrotron oscillations. The instability is damped by this method when the beam current is not high (less than 100 mA). The limitation of this method is in the maximum modulation index available in the experiment. Therefore, the former system is being used in routine operation in spite of its drawback View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • HERA status

    Publication Year: 1989 , Page(s): 431 - 435 vol.1
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    The electron-proton collider HERA (Hadron-Electron Ring Accelerator) consists of two independent accelerators designed to store, respectively, 820-GeV protons and 30-GeV electrons and to collide the counterrotating beams head on in four interaction regions spaced uniformly around its 6.3 km circumference. In addition to HERA, several booster accelerators must either be constructed or modified. The civil engineering work has been completed; electrons were stored for the first time in the HERA electron ring in August 1988. Commissioning of the first two accelerators in the proton injection chain, the 50-MeV H- linear accelerator and the 7.5-GeV DESY III synchrotron, has started. The central helium refrigerators have been running routinely for nearly two years. Production of superconducting magnets is well underway in industry, and the first magnets have already been installed in the tunnel View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The interaction between the third harmonic resonance and parasitic modes inside the TRIUMF cavity

    Publication Year: 1989 , Page(s): 174 - 176 vol.1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    The TRIUMF resonator system has been designed for possible `flat-top' operation. This mode of operation implies simultaneous excitation of the fundamental and the third-harmonic resonances in the same RF cavity. A precise 1:10 scale all-metal model of the TRIUMF cyclotron has been used to study the feasibility of achieving flat-topped operation. The third-harmonic voltage has been shown to vary considerably along the resonator tip due to the higher capacitive loading in the central region. In addition, higher-order parasitic modes of the fundamental group have been observed to interfere with the TEM (transverse electromagnetic mode) third-harmonic resonance, denoted by TEM030, resulting in voltage variations along the dee gap of as much as 10 dB. The observations, a theoretical treatment of the interference, and possible solutions are discussed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamics in an adiabatic free electron laser

    Publication Year: 1989 , Page(s): 932 - 934 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    Theoretical work in progress indicates that an FEL (free-electron laser) with a recirculating beam of electrons might be a practical device, as long as the wiggler parameters change slowly during trapping and detrapping of the beam, so that excessive beam heating does not occur. This could greatly increase the efficiency of a short-wavelength FEL operated in the Compton regime. Standard tapered wigglers are adiabatic for the trapped particles, but these particles are significantly heated each time they enter and exit the wiggler View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Relativistic multipactoring

    Publication Year: 1989 , Page(s): 2008 - 2009 vol.3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (132 KB)  

    A relativistic calculation of the multipactoring condition for the two surfaces phenomenon is presented. The appropriate condition necessary to produce multipactoring is derived from the electronic equation of motion, including the cyclic field across the gap, the peak gap voltage, and the field phase at emission. Particular attention is given to the role of the secondary emission process View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High power RF tests of 433 MHz single-cell accelerator cavities and associated feed system

    Publication Year: 1989 , Page(s): 183 - 185 vol.1
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    The authors describe an accelerator module consisting of four single-cell accelerator cavities powered through the WR 1800 waveguide by a single Thomson-CSF Model 2120 klystron at 433 MHz, for use in the Boeing Modular Components Technology Development electron linac (MCTD). They discuss planned peak and average accelerating field limitation tests and report on the status of the testing program View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.