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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

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

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

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

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

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

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

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

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

Plasma and Beam Production Experiments with HYBRIS, aMicrowave-assisted H- Ion

Description: A two-stage ion source concept had been presented a few years ago, consisting of a proven H- ion source and a 2.45-GHz Electron Cyclotron-Resonance (ECR) type ion source, here used as a plasma cathode. This paper describes the experimental development path pursued at Lawrence Berkeley National Laboratory, from the early concept to a working unit that produces plasma in both stages and creates a negative particle beam. Without cesiation applied to the second stage, the H{sup -} fraction of this beam is very low, yielding 75 micro-amperes of extracted ion beam current at best. The apparent limitations of this approach and envisaged improvements are discussed.
Date: September 13, 2006
Creator: Keller, R. AUTHOR-Kwan, S.; Hahto, S.; Regis, M. & Wallig, J.
Partner: UNT Libraries Government Documents Department

Survey and Alighment for the ALS Project at LBL Berkeley

Description: The Advanced Light Source (ALS), now under construction at Lawrence Berkeley Laboratory, is a synchrotron radiation source of the third generation designed to produce extremely bright photon beams in the UV and soft X-ray regions. Its main accelerator components are a 1-1.9 GeV electron storage ring with 196.8 m circumference and 12 super-periods, a 1.5 GeV booster synchrotron with 75.0 m circumference and 4 super-periods, and a 50 MeV linac, as shown in Fig. 1. The storage ring has particularly tight positioning tolerances for lattice magnets and other components to assure the required operational characteristics. The general survey and alignment concept for the ALS is based on a network of fixed monuments installed in the building floor, to which all component positions are referred. Measurements include electronic distance measurements and separate sightings for horizontal and vertical directions, partially with automated electronic data capture. Most of the data processing is accomplished by running a customized version of PC-GEONET. It provides raw data storage, data reduction, and the calculation of adjusted coordinates, as well as an option for error analysis. PC-GEONET has also been used to establish an observation plan for the monuments and calculate their expected position accuracies, based on approximate coordinates. Additionally, for local survey tasks, the commercial software package ECDS is used. In this paper, the ALS survey and alignment strategy and techniques are presented and critically discussed. First experiences with the alignment of the linac and booster components are described.
Date: August 12, 2005
Creator: Keller, R.; Lauritzen, T.; /LBL, Berkeley; Friedsam, H. & /SLAC
Partner: UNT Libraries Government Documents Department

Status of the SNS H- ion source and low-energy beam transport system

Description: The ion source and Low-Energy Transport (LEBT) system that will provide H{sup -} ion beams to the Spallation Neutron Source (SNS) Front End and the accelerator chain have been developed into a mature unit that will satisfy the operational needs through the commissioning and early operating phases of SNS. The ion source was derived from the SSC ion source, and many of its original features have been improved to achieve reliable operation at 6% duty factor, producing beam currents in the 35-mA range and above. The LEBT utilizes purely electrostatic focusing and includes static beam-steering elements and a pre-chopper. This paper will discuss the latest design features of the ion source and LEBT, give performance data for the integrated system, and report on relevant commissioning results obtained with the SNS RFQ accelerator. Perspectives for further improvements will be outlined in concluding remarks.
Date: April 1, 2002
Creator: Keller, R.; Thomae, R.; Stockli, M. & Welton, R.
Partner: UNT Libraries Government Documents Department