11 Matching Results

Search Results

Advanced search parameters have been applied.

On bunch lengthening using the fourth harmonic cavity in the NSLS VUV ring

Description: It has been suggested that the phase of the beam excited voltage in the harmonic cavity can be controlled by detuning its resonant frequency from the beam current harmonic. Unfortunately the detuning needed to flatten the acceleration waveform also corresponds to the region of Robinson instability for the harmonic cavity. Therefore, lengthening the bunch may be followed by large amplitude synchrotron oscillation of the bunch center of mass. Bunch lengthening is discussed in this note from several points of view. There follows a simple review of single electron oscillations in a quartic potential. Then equations are developed for the coupled oscillations of a cavity and a rigid bunch as a fully nonlinear, time dependent initial value problem. Next, a computer program that solves these equations for one, two or more cavities, with and without externally driven fields, is described and some simulations of the harmonic cavity interaction are shown. Finally, the fully nonlinear equations are linearized to derive a dispersion relation for the case of beam excitation in the harmonic cavity. 6 refs., 5 figs.
Date: February 1, 1988
Creator: Wachtel, J.M.
Partner: UNT Libraries Government Documents Department

Computation of emittance growth in a focusing wiggler FEL (Free Electron Laser)

Description: Computed electron trajectories in a free electron laser show significant emittance growth in the wiggle plane when there are wiggler field gradients. For a low gain free electron laser using a focusing planar wiggler, phase space plots show the development of this 3-dimensional effect as well as rotation of the phase space region occupied by the beam due to betatron oscillations in the focusing wiggler field. Matching the input electron beam to the wiggler eliminates emittance growth. 3 refs., 5 figs., 1 tab.
Date: January 1, 1988
Creator: Ben-Zvi, I. & Wachtel, J.M.
Partner: UNT Libraries Government Documents Department

Validating cognitive support for operators of complex human-machine systems

Description: Modem nuclear power plants (NPPs) are complex systems whose performance is the result of an intricate interaction of human and system control. A complex system may be defined as one which supports a dynamic process involving a large number of elements that interact in many different ways. Safety is addressed through defense-in-depth design and preplanning; i.e., designers consider the types of failures that are most likely to occur and those of high consequence, and design their solutions in advance. However, complex interactions and their failure modes cannot always be anticipated by the designer and may be unfamiliar to plant personnel. These situations may pose cognitive demands on plant personnel, both individually and as a crew. Other factors may contribute to the cognitive challenges of NPP operation as well, including hierarchal processes, dynamic pace, system redundancy and reliability, and conflicting objectives. These factors are discussed in this paper.
Date: October 1995
Creator: O`Hara, J. & Wachtel, J.
Partner: UNT Libraries Government Documents Department

Rf stability, control and bunch lengthening in electron synchrotron storage rings

Description: A self-consistent theory for nonlinear longitudinal particle motion and rf cavity excitation in a high energy electron storage ring is developed. Coupled first order equations for the motion of an arbitrary number of particles and for the field in several rf cavities are given in the form used in control system theory. Stochastic quantum excitation of synchrotron motion is included, as are the effects of rf control system corrections. Results of computations for double cavity bunch lengthening are given. 11 refs., 4 figs., 1 tab.
Date: September 1, 1989
Creator: Wachtel, J.M.
Partner: UNT Libraries Government Documents Department

Advanced alarm systems: Display and processing issues

Description: This paper describes a research program sponsored by the US Nuclear Regulatory Commission to address the human factors engineering (HFE) deficiencies associated with nuclear power plant alarm systems. The overall objective of the study is to develop HFE review guidance for alarm systems. In support of this objective, human performance issues needing additional research were identified. Among the important issues were alarm processing strategies and alarm display techniques. This paper will discuss these issues and briefly describe our current research plan to address them.
Date: May 1, 1995
Creator: O`Hara, J.M.; Wachtel, J. & Perensky, J.
Partner: UNT Libraries Government Documents Department

Methodological issues in the validation of complex human-machine systems

Description: Integrated system validation is one aspect of the US Nuclear Regulatory Commission`s design review process for human-system interfaces. This paper will consider three methodological issues that must be addressed in validation and their implications for drawing conclusions about the acceptability of the integrated system. They are: representing the integrated system, representing the operational events it must handle, and representing system performance. A logical basis for generalizability from validation tests to predicted performance of the integrated system emerges from the comparability of the psychological and physical processes of the test and actual situations. Generalizability of results is supported when the integrated system, operating conditions and performance are representative of their real-world counterparts. The methodological considerations for establishing representativeness are discussed.
Date: May 1, 1995
Creator: O`Hara, J.; Stubler, W. & Wachtel, J.
Partner: UNT Libraries Government Documents Department

Optics of beam transport in the NSLS uv-FEL

Description: The NSLS-FEL is designed as a single pass FEL to generate radiation 1 mJ per pulse (10 psec) in 10{sup {minus}4} bandwidth, with continuously tunable wavelength in the range 100--300 nm. A superconducting, recirculating linac provides electron beams of energy 20 MeV to 260 MeV at 4{pi} mm mrad normalized rms emittance with less than 0.1% momentum spread and 2 mm rms bunch length. The optics in this machine is seriously restricted by the requirement to not degrade the electron beam quality. We present a lattice design for the transport lines to be used in beam injection, linac focussing and recirculations. These beam lines are tuned to be linearly achromatic and isochronous, to avoid beam breakup in the cavities, and to minimize second order distortions of the emittance. Special transport lines are designed that allow rapid switching of the electron beam to drive two different FEL wigglers. This provides the capability for up to four simultaneous, high power, independently energy tuned laser beam.
Date: January 1, 1992
Creator: Zhang, X.; Kramer, S.L. & Wachtel, J.
Partner: UNT Libraries Government Documents Department

The use of simulation in the development of human factors guidelines for alarm systems

Description: This paper describes a research program sponsored by the US Nuclear Regulatory Commission to address the human factors engineering (HFE) aspects of nuclear power plant alarm systems. The overall objective of the program is to develop HFE review guidance for advanced alarm systems. As part of this program, guidance was developed based on a broad review and analysis of technical and research literature. In the course of guidance development, aspects of alarm system design for which the technical basis was insufficient to support guidance developed were identified. Experimental research is currently underway to address the highest priority topics: alarm processing and display characteristics. This paper provides an overview of the approach to guidance development and discusses the role of simulation in the development approach. Finally, the current simulator-based experiment is described to illustrate how the alarm system design features are being studied.
Date: July 1, 1997
Creator: O`Hara, J.; Brown, W.S.; Hallbert, B.; Skraaning, G.; Wachtel, J. & Persensky, J.
Partner: UNT Libraries Government Documents Department


Description: The Human-System Interface Design Review Guideline (NUREG-0700, Revision 1) was developed by the US Nuclear Regulatory Commission (NRC) to provide human factors guidance as a basis for the review of advanced human-system interface technologies. The guidance consists of three components: design review procedures, human factors engineering guidelines, and a software application to provide design review support called the ``Design Review Guideline.'' Since it was published in June 1996, Rev. 1 to NUREG-0700 has been used successfully by NRC staff, contractors and nuclear industry organizations, as well as by interested organizations outside the nuclear industry. The NRC has committed to the periodic update and improvement of the guidance to ensure that it remains a state-of-the-art design evaluation tool in the face of emerging and rapidly changing technology. This paper addresses the current research to update of NUREG-0700 based on the substantial work that has taken place since the publication of Revision 1.
Date: July 30, 2000
Partner: UNT Libraries Government Documents Department

Advanced control room evaluation: General approach and rationale

Description: Advanced control rooms (ACRs) for future nuclear power plants (NPPs) are being designed utilizing computer-based technologies. The US Nuclear Regulatory Commission reviews the human engineering aspects of such control rooms to ensure that they are designed to good human factors engineering principles and that operator performance and reliability are appropriately supported in order to protect public health and safety. This paper describes the rationale and general approach to the development of a human factors review guideline for ACRs. The factors influencing the guideline development are discussed, including the review environment, the types of advanced technologies being addressed, the human factors issues associated with advanced technology, and the current state-of-the-art of human factors guidelines for advanced human-system interfaces (HSIs). The proposed approach to ACR review would track the design and implementation process through the application of review guidelines reflecting four review modules: planning, design process analysis, human factors engineering review, and dynamic performance evaluation. 21 refs.
Date: January 1, 1991
Creator: O'Hara, J.M. (Brookhaven National Lab., Upton, NY (USA)) & Wachtel, J. (Nuclear Regulatory Commission, Washington, DC (USA))
Partner: UNT Libraries Government Documents Department

Proposed uv-FEL user facility at BNL

Description: The NSLS at Brookhaven National Laboratory is proposing the construction of a UV-FEL operating in the wavelength range from visible to 750{Angstrom}. Nano-Coulomb electron pulses will be generated at a laser photo-cathode RF gun at a repetition rate of 10 KHz. The 6 ps pulses will be accelerated to 250 MeV in a superconducting linac. The FEL output will serve four stations with independent wavelength tuning, using two wigglers and two rotating mirror beam switches. Seed radiation for the FEL amplifiers will be provided by conventional tunable lasers, and the final frequency multiplication from the visible or near UV to the VUV will be carried out in the FEL itself. Each FEL will comprise of an initial wiggler resonant to the seed wavelength, a dispersion section, and a second wiggler resonant to the output wavelength. The facility will provide pump probe capability, FEL or FEL, and FEL on synchrotron light from an insersion device on the NSLS X-Ray ring. 15 refs., 2 figs., 3 tabs.
Date: January 1, 1991
Creator: Ben-Zvi, I.; Di Mauro, L.F.; Krinsky, S.; White, M.G.; Yu, L.H.; Batchelor, K. et al.
Partner: UNT Libraries Government Documents Department