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High-brightness, high-current ion sources

Description: Several existing high-current dc ion sources are presented that yield positive ions and are based on gas discharges. Their common features are then outlined: extraction systems, required plasma qualities, and the production of ions from solid materials. Finally, from well-established laws, scaling rules for high-brightness ion beams are derived taking one specific case to determine the numerical constants. These rules predict that the current values of transportable beams scale proportionally to the 3/2 power of the extraction voltage, whereas the brightness strongly decreases with rising voltage.
Date: January 1, 1985
Creator: Keller, R.
Partner: UNT Libraries Government Documents Department

Magnetic data analysis for the ALS lattice magents

Description: The Advanced Light Source (ALS), now under construction at Lawrence Berkeley Laboratory, is a third-generation synchrotron radiation source designed to produce extremely bright photon beams in the UV and soft X-ray regions. The lattice magnets to be installed in the two rings, a 1--1.9 GeV storage ring, and a 1.5 GeV booster synchrotron, have been magnetically measured to ascertain their excitation curves and field uniformity. In this paper the analysis of these data is discussed, and results for measured magnets are given. 5 refs., 2 figs., 7 tabs.
Date: May 1, 1991
Creator: Keller, R.
Partner: UNT Libraries Government Documents Department

Spectroscopic measurements of an H/sup -/ ion source discharge

Description: Spectral emission lines from an H/sup -/ Penning surface-plasma source (SPS), the 4X source, are examined in the visible and near ultraviolet. Electron distribution temperatures are deduced from integral line-strength measurements. These temperatures are surprisingly low, about 0.5 eV. Electron density values of about 1.5 x 10/sup 14/ cm/sup -3/ and H-atom energies between 2 and 2.6 eV are determined from the measured Balmer-line profiles. Assuming the H/sup -/ energy is identical to the H-atom energy, an emittance limit of 0.006 ..pi.. x cm x mrad is deduced for this source with a 5.4-mm aperture.
Date: January 1, 1985
Creator: Keller, R. & Smith, H.V. Jr.
Partner: UNT Libraries Government Documents Department

Hysteresis and saturation effects with the ALS lattice magnets

Description: The primary purpose of the magnetic measurements performed on the ALS storage ring lattice magnets was to ascertain their compliance with the strict tolerances established for this third-generation synchrotron light source. In the course of the data evaluation, an approximation method has been developed that leads to four-parameter representations of all magnet transfer functions. The expressions for the transfer functions were now used to change the standard working point of the ALS storage ring from the upper to the lower hysteresis branches of all lattice magnet families, and later to ramp the ring from the customary 1.5 GeV to the maximum design energy of 1.9 GeV in one uninterrupted process that did not require any intermediate tune correction. This achievement is all the more remarkable as no remnant fields had directly been measured with any of these magnets. A specific remnant field effect that led to anomalous machine behavior-when trying to recuperate the betatron tunes on the lower hysteresis branch at standard energy could be ascribed to the C-shape of the quadrupole yokes.
Date: April 1, 1995
Creator: Keller, R.
Partner: UNT Libraries Government Documents Department

Survey and alignment analysis for the ALS storage ring using computer spreadsheets

Description: The general survey and alignment concept for the ALS is based on a network of fixed, three-dimensional monuments installed in the building floor, to which all accelerator component positions are referred. The survey of these monuments is performed separately for horizontal and vertical coordinates, following the scheme imposed by the code PC-GEONET that is used for monument data analysis. For most of the accelerator objects the tasks of data acquisition, bundling, and transformations from observation-station into object coordinate-systems are being handled by the commercial software package ECDS rather than by PC-GEONET. This choice had to be made because no instrument stands are presently available at LBL that can be placed exactly over monuments and are high enough to permit observing the fiducials of installed magnets from above. Theodolites only are used with ECDS as observation instruments, and absolute scaling has to be provided by observing some object of precisely known length. To create ideal data and compute alignment values for all accelerator components, spreadsheets were developed by the author using the application EXCEL for Macintosh computers. Choice of a spreadsheet method rather than conventional programming techniques proved very convenient when in the course of this work the sheets had to be created and progressively modified under severe time pressure to include new effects and help redefine the observation procedures. With spreadsheets, varying input data formats coming from the survey crew could be easily accommodated, and adding numerous consistency checks as well as generating additional ideal data for special alignment tasks was possible with comparatively little effort. Dedicated spreadsheets were created for each of the 12 curved sectors of the storage ring. In this paper, the main features of the spreadsheets are presented, and the alignment results for lattice and corrector magnets are listed and discussed.
Date: July 1, 1993
Creator: Keller, R.
Partner: UNT Libraries Government Documents Department

Survey and alignment data analysis for the ALS storage ring

Description: The survey and alignment effort for the Advanced Light Source (ALS) accelerator complex has been described elsewhere. Data analysis for this task comprises the creation of ideal data, comparison of measured coordinates with ideal ones, and computation of alignment values, taking into account the effects caused by finite observation accuracy. A novel approach has been taken, using personal computer spreadsheets rather than more conventional programming methods. This approach was induced by the necessities to create and frequently refine the analysis procedures while measurements were already underway, and further by hardware constraints that limited the use of an available surveying code. A major benefit consists in the ability to identify and deal with discrepancies that occasionally arise when different techniques are used to observe the same object, in a timely and efficient manner. As a result of the performed survey and alignment work, the ALS lattice magnets have been positioned with accuracies well exceeding the original specifications.
Date: May 1, 1993
Creator: Keller, R.
Partner: UNT Libraries Government Documents Department

Final analysis of the ALS lattice magnet data

Description: A preliminary analysis of the measured magnet data of the multipole magnets to be installed in the Advanced Light Source (ALS) storage ring had been given in the last conference of this series. That analysis was based on measurements of about one-third of the entire magnet complement, and some of its findings had to be revised after obtaining more data. The present paper gives an account of the integrated fundamental field strengths of all installed storage ring lattice magnets. For the multipole magnets, these values are listed as analytical expressions with four or five parameters, that cover the entire excitation range and include residual strength. Based on this final analysis, all gradient and quadrupole magnets were qualified for installation, whereas the sextupole magnets had to be individually trimmed to bring their effective fundamental strengths into the desired tolerance band.
Date: May 1, 1993
Creator: Keller, R.
Partner: UNT Libraries Government Documents Department

Primary ion sources for EBIS

Description: This paper gives an introduction into the topic of primary ion sources that can be used to feed ions of normally solid elements into EBIS devices. Starting with a set of typical requirements for primary ion sources, some major types of ion generators are discussed first, with emphasis on their working principles rather than trying to give a fully representative listing of used and proposed generators. Beam-transport issues between primary ion source and EBIS are then examined, and generic characteristics of suitable beam-formation and transport systems are explained.
Date: March 21, 2001
Creator: Keller, R.
Partner: UNT Libraries Government Documents Department

The SNS front-end, an injector for a high-power hydrogen-ion accelerator

Description: The Spallation Neutron Source (SNS) will be an accelerator-based facility in Oak Ridge, TN, delivering pulsed neutron beams to experimenters. Negative hydrogen ion-beams are generated and pre-accelerated in a 2.5-MeV linac injector, or front end (FE), accelerated to 1 GeV energy by a linear accelerator system, converted into protons and accumulated in a ring accelerator, and then directed towards a mercury target to generate the neutrons. The proton beam arrives at the target in bursts of less than 1 {micro}s duration and with more than 1 MW average power. The front end has been built and commissioned by LBNL in Berkeley; shipment to ORNL is essentially complete. This paper provides an overview of FE major design features and experimental results obtained during the commissioning process. The SNS-FE can be viewed as a prototype of a high-current, high duty-factor injector for other accelerator projects or, without the elaborate MEBT, as an independent 2.5-MeV accelerator for various applications.
Date: February 1, 2002
Creator: Keller, R.
Partner: UNT Libraries Government Documents Department

AC magnetic measurements of the ALS Booster Synchrotron Dipole Magnet engineering model

Description: We made a minimal set of AC magnetic measurements of the engineering model of the ALS Booster Dipole Magnet as part of the process of qualifying its design for production. Magnetic induction integrals over paths approximating electron-beam trajectories were measured with long curved coils connected to an electronic integrator. Magnetic induction was measured with point coils and an integrator and independently with a Hall-effect Gaussmeter. These quantities, and magnet current, were displayed on a commercial digital storage oscilloscope as parametric functions of time. The displayed waveforms were stored, processed and redisplayed as representations of selected magnet parameters. A waveform representing the magnet's effective-length was created by dividing the integral waveform by the magnetic induction waveform. Waveforms of the transfer functions were produced by dividing both the integral waveform and the magnetic induction waveform by the current waveform. Pairs of matched coils, connected in series opposition, provided differential measurements of field uniformity. Quadrupole and sextupole coefficients were derived from the uniformity data. These magnet parameters were measured at 2 and 10 Hz frequencies. Together with measurements of the magnetic field at selected dc levels, the ac measurements demonstrated that the magnet design met specifications and qualified it for production. 7 refs., 7 figs., 3 tabs.
Date: September 1, 1988
Creator: Green, M.I.; Hoyer, E.; Keller, R. & Nelson, D.H.
Partner: UNT Libraries Government Documents Department

Atlas of uranium emission intensities in a hollow cathode discharge

Description: The uranium emission spectrum from a hollow cathode discharge is displayed from 11,000 to 26,000 cm/sup -1/. This atlas lists 4928 spectral lines of uranium; 3949 are classified to the neutral spectrum and 431 are classified to the singly ionized spectrum. Listed wavenumbers are accurate to +-0.003 cm/sup -1/ and the listed relative intensities to +-8%. The richness of the spectrum makes this atlas useful for wavenumber calibration of lasers, spectrographs, and monochromators to an accuracy of 1 part in 10/sup 7/. This atlas is also useful as a guide to the uranium spectrum, and relative oscillator strengths (gf values) can be calculated from the intensities to a precision of +-20%.
Date: July 1, 1980
Creator: Palmer, B.A.; Keller, R.A. & Engleman, R. Jr.
Partner: UNT Libraries Government Documents Department

A high charge state multicusp ion source

Description: Attempts have been made to generate high charge state ion beams by employing a multicusp plasma source. Three experimental investigations have been performed at LBL and at GSI to study the charge state distributions and the emittance of the extracted beam. Results demonstrate that charge state as high as +7 can be obtained with argon or xenon plasmas. The brightness of a 11 mA xenon ion beam is found to be 26 A/({pi}-mm-mrad){sup 2}. 6 refs., 6 figs.
Date: June 1, 1989
Creator: Leung, K.N. & Keller, R.
Partner: UNT Libraries Government Documents Department

Power plant performance analysis and guidelines study. Appendix III. Reliability and efficiency index data

Description: Historical data from the EEI, FPC, NRC, FEA, and participating utilities were evaluated for each of the four reliability and efficiency indices recommended to the California Energy Commission. Data were not available for all unit sizes for the full period 1971 to 1975. However, the available data were analyzed to arrive at historical averages and ranges of averages for each of the recommended indices. Feasible ranges and averages of each index for units of different sizes and fuel types are presented and trends for each index are discussed with respect to characteristics such as unit age, maturity, equipment problems, etc. The recommended application of these data to the power plant Reliability and Efficiency Guidelines are discussed in the main body of this report (Section B).
Date: June 1, 1978
Creator: Keller, R W; Bhatla, A & Smith, M J
Partner: UNT Libraries Government Documents Department

Power plant performance analysis and guidelines study. Appendix I. Recommended guideline for siting power plants

Description: This initial guideline is issued to describe and make available to the public methods acceptable to the California Energy Commission staff of implementing specific parts of the Commission's regulations and provide guidance to applicants desiring to site new power plants in the State of California. Information is included on establishing the most cost-effective levels or ranges of reliability and efficiency and on applicants actions to ensure the achievement of established reliability and efficiency levels and ranges. (LCL)
Date: June 1, 1978
Creator: Keller, R W; Bhatla, A & Smith, M J
Partner: UNT Libraries Government Documents Department

Power plant performance analysis and guidelines study. Appendix II. Reliability and efficiency indices

Description: Four indices of power plant performance have been identified for use by the CERCDC in the technical evaluation of cost-effective levels of reliability and efficiency of future power plants, to be sited in the State of California. The selected indices are Capacity Factor, Operating Availability, Equivalent Availability, and Heat Rate. The write-up on each index includes a discussion on the Index Definition, Historical Data Availability/Sources and Recommendations for Application by the Commission.
Date: June 1, 1978
Creator: Keller, R W; Bhatla, A & Smith, M J
Partner: UNT Libraries Government Documents Department

Name management in the construction of large programs. [Modular decomposition, programmed in PL/I for IBM 360/65]

Description: There has been much recent work on the problem of constructing large programs. One aspect of this problem that has been somewhat ignored is the management of names during the program construction process. A framework emphasizing this aspect of the problem is presented. Linguistic constructs for the manipulation of names between independently written pieces of text are defined. An implementation model defining the effect of these constructs on the naming structure of the resulting language is presented. The implementation model is demonstrated in terms of an example to illustrate the usefulness of the framework.
Date: August 1, 1976
Creator: Carr, P. A.; Keller, R. F. & Wright, C. T. Jr.
Partner: UNT Libraries Government Documents Department

Spectroscopic investigation of H/sup -/ and D/sup -/ ion source plasmas

Description: Several H I (Balmer), Cs I, Cs II, and Mo I lines emitted by the small-angle source and 4X source plasmas are studied. After correcting for Stark broadening, the H/sub ..cap alpha../ line width gives the H-atom temperature kT/sub H/o. After correcting for Doppler broadening, the H/sub ..beta../ and H/sub delta/ line widths give the electron density n/sub e/. For pulsed operation of both sources, kT/sub H/o is 1.5 to 2 eV and n/sub e/ is 1 to 2 x 10/sup 14//cm/sup 3/, with kT/sub H/o and n/sub e/ scaling approximately with the square root of the discharge current. For the 4X source operated on D/sub 2/, kT/sub D/o and n/sub e/ are near the values of kT/sub H/o and n/sub e/ obtained for H/sub 2/ operation. Assuming that the H/sup -//D/sup -/ ion temperature equals the H/D-atom temperature, we deduce a lower limit to the H/sup -//D/sup -/ beam emittance.
Date: October 1, 1986
Creator: Smith, H.V. Jr.; Allison, P. & Keller, R.
Partner: UNT Libraries Government Documents Department

AC magnetic measurements of the ALS Booster Dipole Engineering Model Magnet

Description: 10 Hz sine wave and 2 Hz sawtooth AC magnetic measurements of he curved ALS Booster Dipole Engineering Model Magnet have been accomplished. Long curved coils were utilized to measure the integral transfer function and uniformity. Point coils and a Hall Probe were used to measure magnetic induction and its uniformity. The data were logged and processed by a Tektronix 11401 digital oscilloscope. The dependence of the effective length on the field was determined from the ratio of the integral coil signals to the point coil signals. Quadrupole and sextupole harmonics were derived from the point and integral uniformity measurements. 5 refs., 4 figs., 2 tabs.
Date: March 1, 1989
Creator: Green, M.I.; Keller, R.; Nelson, D.H. & Hoyer, E.
Partner: UNT Libraries Government Documents Department