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Fluorescence Rise Time Measurements for High Temperature Fluorescence-Based Thermometry

Description: Certain ceramic-like phosphor materials exhibit bright fluorescence with a pronounced temperature dependence over a range which spans the cryogenic to 1700 C, depending on the specific phosphor. To measure temperature, a surface, for instance a turbine blade, is coated with the material. An optical system, sometimes including optical fibers, conveys stimulating light and collects the emission for analysis. Either emission intensity or decay time may indicate temperature. Previously fielded tests have involved surfaces such as blades, vanes, pistons, in-take valves, sheets of galvanneal steel, etc. The fluorescent coatings may be applied to small parts via sputtering methods or to large areas by mixture with inorganic binders. Presented here are results characterizing fluorescence rise times as a means of determining temperature from ambient to 700 C for Y{sub 2}O{sub 3}:Eu.
Date: March 24, 2005
Creator: Allison, S.W.
Partner: UNT Libraries Government Documents Department

Sub-Microsecond Decay Time Phosphors for Pressure Sensitive Paint Applications

Description: The results suggest that garnet phosphors can be engineered to function thermographically over desired temperature ranges by adjusting gallium content. Substituting gadolinium for the yttrium in the host matrix also has an effect but it is not as large. A silicate phosphor showed the greatest temperature dependence though it could not be excited to fluoresce by a blue LED. All the garnet phosphors could be excited with such a blue source. Two phosphors tested showed an increase in intensity with temperature. Other garnet and silicate materials as mentioned above will be tested in the future. In addition, some perovskite phosphors, such as GdAlO{sub 3}:Ce, will also be investigated.
Date: March 22, 2001
Creator: Allison, S.W.
Partner: UNT Libraries Government Documents Department

LED-induced fluorescence diagnostics for turbine and combustion engine thermometry

Description: Fluorescence from phosphor coatings is the basis of an established technique for measuring temperature in a wide variety of turbine and combustion engine applications. Example surfaces include blades, vanes, combustors, intake valves, pistons, and rotors. Many situations that are remote and noncontact require the high intensity of a laser to illuminate the phosphor, especially if the surface is moving. Thermometric resolutions of 0.1 C are obtainable, and some laboratory versions of these systems have been calibrated against NIST standards to even higher precision. To improve the measurement signal-to-noise ratio, synchronous detection timing has been used to repeatedly interrogate the same blade in a high speed rotating turbine. High spatial resolution can be obtained by tightly focusing the interrogation beam in measurements of static surfaces, and by precise differential timing of the laser pulses on rotating surfaces. We report here the use of blue light emitting diodes (LEDs) as a n illumination source for producing useable fluorescence from phosphors for temperature measurements. An LED can excite most of the same phosphors used to cover the temperature range from 8 to 1400 C. The advantages of using LEDs are obvious in terms of size, power requirements, space requirements and cost. There can also be advantages associated with very long operating lifetimes, wide range of available colors, and their broader emission bandwidths as compared to laser diodes. Temperature may be inferred either from phase or time-decay determinations.
Date: August 17, 2001
Creator: Allison, S. W.
Partner: UNT Libraries Government Documents Department

High Temperature Surface Measurements Using Lifetime Imaging of Thermographic Phosphors: Bonding Tests

Description: Temperature-sensitive paint (TSP) comprised of thermally sensitive phosphor can provide a viable means for noncontact thermometry in wind tunnel and other aeropropulsion applications. Described here are recent results aimed at developing a phosphor and binder system that will cover a wide temperature range, ambient to 1000 C. The phosphor/binder mixture is to be sprayed directly on the surface with an airbrush. Whereas many surfaces are candidates for various uses, the present effort concerned silicon carbide, silicon nitride and silica substrates. Initial tests show that a phosphor mixture with two water-soluble materials, designated LK and HPC and manufactured by ZYP Inc., adhered well to these substrates. This same material was earlier shown to function well on a high strength nickel alloy.
Date: October 29, 2001
Creator: Allison, S. W.
Partner: UNT Libraries Government Documents Department

Galvanneal Thermometry with a Thermographic Phosphor System

Description: The accurate determination of temperature of galvanneal sheet emerging from a zinc bath is a challenging process measurement. The line moves at high speeds, up to 900 feet per minute, and the emissivity varies widely as it moves through the radio-frequency (RF) induction heating ovens and subsequently cools. This presents a great source of error if the pyrometric approach is used since the accuracy is sensitive to emissivity variation. This problem has been circumvented by an approach described here which uses a thermally sensitive phosphor technique for temperature measurement. For this, a small amount of a phosphor material is deposited on the liquid surface of the sheet. When the small layer of phosphor moves to the measurement station, it is illuminated by a short laser pulse which produces fluorescence from the material. The time dependence of the fluorescence indicates the temperature. Introduction of the microgram quantities of material has been shown to have no detrimental impact on product quality! This presentation describes a phosphor-based system for measuring temperature on a galvanneal manufacturing line. To date, measurements with an accuracy of +/- 5 deg F have been made at National Steel=s Midwest facility. This effort is a part of the Advanced Process Controls Program. The overall goal of the project is to provide accurate on-line temperature information that can be used to increase the yield and quality of the product, thereby reducing energy consumption and time.
Date: December 31, 1997
Creator: Manges, W.W., Allison, S.W.
Partner: UNT Libraries Government Documents Department

AISI/DOE Advanced Process Control Program Vol. 6 of 6: Temperature Measurement of Galvanneal Steel

Description: This report describes the successful completion of the development of an accurate in-process measurement instrument for galvanneal steel surface temperatures. This achievement results from a joint research effort that is a part of the American Iron and Steel Institute's (AISI) Advanced Process Control Program, a collaboration between the U.S> Department of Energy and fifteen North American Steelmakers. This three-year project entitled ''Temperature Measurement of Galvanneal Steel'' uses phosphor thermography, and outgrowth of Uranium enrichment research at Oak Ridge facilities. Temperature is the controlling factor regarding the distribution of iron and zinc in the galvanneal strip coating, which in turn determines the desired product properties
Date: June 30, 1999
Creator: Allison, S. W.; Beshears, D. L. & Manges, W. W.
Partner: UNT Libraries Government Documents Department

Non-contact phosphor thermometry for process control

Description: Manufacturing and other industrial processes often require monitoring and control of temperature. Thermometry based on fluorescence properties of surface-bonded phosphors offers a number of advantages over traditional methods. The method is non-contact, remote, and independent of surface optical properties such as emissivity. Only a thin layer, less than 50 microns thick, is required of fluorescent materials that are temperature-active and chemically stable up to temperatures in excess of 1600 C. Phosphor thermometry has been developed from these high temperature extremes all the way down to cryogenic temperatures within liquid helium dewars. The fluorescence effects are stable in time, not subject to drift and repeated need for recalibration. Measurement techniques often involve use of optical fibers and other components that allow access into confined geometries and environments with high vibration, electromagnetic fields, or other extreme conditions. Uses include thermal management of cutting or shaping tools, monitoring of furnace and combustor walls or internal components, assembly components in automated lines, sheet metal surface thermometry, measurement of rotating components in motors, generators, turbine engines, and similar systems, fiber temperature measurement in textile fiber spinning, etc. Fluorescence measurement yields absolute temperatures, not dependent on references, and can have accuracies of less than 1 K, with precisions well below 0.1 K, providing opportunity for ultra high precision process control, life testing, and quality control.
Date: August 1, 1996
Creator: Cates, M.R.; Beshears, D.L. & Allison, S.W.
Partner: UNT Libraries Government Documents Department

Application of phosphor thermometry to galvanneal processing

Description: A system has been developed for determining temperatures of galvanneal steel during the production process. It is based on an optical method known as phosphor thermometry and it provides for reliable, emissivity-independent measurements. This development is a part of the American Iron and Steel Institute`s (AISI) Advanced Process Control Program, a joint endeavor between the AISI and the U.S. Department of Energy. Galvanneal is a corrosion-resistant steel that is widely used for automotive and other applications. Improved thermometry should enable steelmakers to significantly improve product quality as well as to increase the yield. ultimately decreasing costs.
Date: May 8, 1997
Creator: Beshears, D.L.; Abston, R.A. & Allison, S.W.
Partner: UNT Libraries Government Documents Department

Fluorescence thermometry for advanced high-temperature materials

Description: Advanced high-temperature materials, such as ceramics, metals, and composites, are of critical importance to the development of new and improved technologies worldwide. For aircraft, automobiles, or other combustion-engine powered systems, major efficiency improvements depend on the ability to operate at temperatures closer to the adiabatic limit of the chemical processes involved. Materials able to function at higher temperatures must therefore be introduced into improved designs. Jet turbine engines, for example, already require air cooled rotors and stators in order that the nickel alloys used will not deteriorate and fail from overheating. In the case of ceramics, optimum temperature usage will often cause the refractory surfaces to glow red hot and the material itself to become partially translucent. For composites, especially where structural integrity, vibration resistance, and strength are concerned, the temperature behavior of dissimilar components must be well known and well understood before appropriate designs can be effected. As the need for higher temperature materials becomes increasingly more important, so does the requirement to properly measure the temperatures involved. Phosphor thermometry offers measurement solutions at very high temperatures that often cannot be achieved by more conventional methods. In this paper we discuss the phosphor technique and several examples of its application to high-temperature measurement.
Date: May 1, 1996
Creator: Cates, M.R.; Beshears, D.L. & Allison, S.W.
Partner: UNT Libraries Government Documents Department

Operator interface for the PEP-II low level RF control system

Description: This paper focuses on the operational aspects of the low level RF control system being built for the PEP-II storage rings at SLAC. Subsystems requiring major operational considerations include displays for monitor and control from UNIX workstations, slow feedback loops and control sequences residing on microprocessors, and various client applications in the existing SLAC Linear Collider (SLC) control system. Since commissioning of PEP-II RF is currently in-progress, only those parts of the control system used during this phase are discussed in detail. Based on past experience with the SLC control system, it is expected that effort expended during commissioning on a solid user interface will result in smoother transition to full reliable 24-hour-a-day operation.
Date: May 1, 1997
Creator: Allison, S. & Claus, R.
Partner: UNT Libraries Government Documents Department

Status and results from the next linear collider test accelerator

Description: The design for the Next Linear Collider (NLC) at SLAC is based on two 11.4 GHz linacs operating at an unloaded acceleration gradient of 50 MV/m increasing to 85 MV/m as the energy is increased from {1/2} TeV to 1 TeV in the center of mass. During the past several years there has been tremendous progress on the development of 11.4 GHz (X-band) RF systems. These developments include klystrons which operate at the required power and pulse length, pulse compression systems that achieve a factor of four power multiplication and structures that are specially designed to reduce long-range wakefields. Together with these developments, we have constructed a {1/2} GeV test accelerator, the NLC Test Accelerator (NLCTA). The NLCTA will serve as a test bed as the design of the NLC is refined. In addition to testing the RF system, the NLCTA is designed to address many questions related to the dynamics of the beam during acceleration, in particular the study of multibunch beam loading compensation and transverse beam break-up. In this paper we present the status of the NLCTA and the results of initial commissioning.
Date: August 1, 1996
Creator: Ruth, R.D.; Adolphsen, C. & Allison, S.
Partner: UNT Libraries Government Documents Department

Results from the SLAC NLC test accelerator

Description: The design for the Next Linear Collider (NLC) at SLAC is based on two 11.4 GHz linacs operating at an unloaded acceleration gradient of 50 MV/m increasing to 85 MV/m as the energy is increased from 1/2 TeV to 1 TeV in the center of mass. During the past several years there has been tremendous progress on the development of 11.4 GHz (X-band) RF systems. These developments include klystrons which operate at the required powder and pulse length, pulse compression systems that achieve a factor of four power multiplication and structures that are specially designed to reduce long-range wakefields. Together with these developments, we have constructed a 1/2 GeV test accelerator, the NLC Test Accelerator (NLCTA). The NLCTA will serve as a test bed as the design of the NLC is refined. In addition to testing the RF system, the NLCTA is designed to address many questions related to the dynamics of the beam during acceleration, in particular, multibunch beam-loading compensation and transverse beam break-up. In this paper we describe the NLCTA and present results from initial experiments.
Date: June 1, 1997
Creator: Ruth, R.D.; Adolphsen, C. & Allison, S.
Partner: UNT Libraries Government Documents Department

Measurement of gas density and temperature profiles in UF/sub 6/ using laser induced fluorescence

Description: Laser induced fluorescence (LIF) can be used to determine the pressure and temperature of an UF/sub 6/ gas sample. An external pulsed laser is used to excite the gas and a multichannel fiber optics system simultaneously collects fluorescence signals emanating from a number of points in the gas. The signals are digitized and presented to a minicomputer for data reduction. Both fluorescence intensity and lifetime are used to deduce temperature and pressure. The LIF probe system is described. Analysis of the data is discussed, and representative results are presented.
Date: January 1, 1985
Creator: Caldwell, S.E.; Gentry, R.A.; White, R.W. & Allison, S.W.
Partner: UNT Libraries Government Documents Department

Thermographic properties of eight blue-emitting phosphors

Description: We examined the effect of temperature on the light emission and absorption properties of eight phosphorescent compounds. The phosphors are commercially produced powders that emit mainly in the blue region when illuminated with ultraviolet light (220 to 400 nm). Excitation and emission spectra taken over the temperature range of 20 to 350C are presented for these phosphors. Data from the spectra indicate a strong temperature dependence over this temperature range. Maximum relative intensity changed as a function of temperature in every phosphor examined. In some samples, spectral band shifts and bandwidths also changed with temperature. Of these phosphors, BaMg[sub 2]Al[sub 16]O[sub 27]:Eu and Ba[sub 3](PO[sub 4])[sub 2]:Eu are candidates for higher-temperature studies.
Date: January 1, 1993
Creator: Cunningham, D.M.; Allison, S.W. & Smith, D.B.
Partner: UNT Libraries Government Documents Department

The LCLS Timing Event System

Description: The Linac Coherent Light Source requires precision timing trigger signals for various accelerator diagnostics and controls at SLAC-NAL. A new timing system has been developed that meets these requirements. This system is based on COTS hardware with a mixture of custom-designed units. An added challenge has been the requirement that the LCLS Timing System must co-exist and 'know' about the existing SLC Timing System. This paper describes the architecture, construction and performance of the LCLS timing event system.
Date: July 23, 2012
Creator: Dusatko, John; Allison, S.; Browne, M.; Krejcik, P. & /SLAC
Partner: UNT Libraries Government Documents Department

Single-point diamond turning of lead indium phosphate glass

Description: The development of the ability to routinely machine glass materials to optical tolerances is highly desirable and, in particular, could provide new degrees of control over the precise shape of complex and unusual optical surfaces. Of particular interest in this regard is the formation of non-spherical shapes where there is a need to fabricate both inexpensive, low-precision optics as well as specialized high-precision aspheric components. This work describes the initial feasibility tests of the machining of a new type of glass, lead indium phosphate (LIP), a material which transmits from the visible to 2.8 micrometers (for thin samples). Glossy surfaces were produced with a root-mean-square surface roughness of less than 100 nm (with 200 micrometer filter). The results indicate that this approach offers the potential for producing high-quality aspheric optical shapes based on the use of LIP glass.
Date: August 1, 1996
Creator: Allison, S.W.; Cunningham, J.P.; Rajic, S.; Boatner, L.A. & Sales, B.C.
Partner: UNT Libraries Government Documents Department

A wide-range phosphor thermometry technique

Description: Fluorescing materials exhibit a temperature dependence, which may be exploited for thermometry purposes. Solid state materials such as phosphors, glasses and crystals are examples of such and have been used in commercial instruments and various one-of-a- kind research and development applications. This area has been the subject of previous ISA papers. It is generally the case that fluorescence decay time or lifetime is the parameter that is measured in order to determine temperature for applications that do not require imaging. There are several good reasons for this. The decay time is a very sensitive function of temperature. Time- and rate-dependent methods are independent of amplitude fluctuations and are therefore not as susceptible to optical noise. In some applications, however, other aspects of the temperature-dependent fluorescence can also be useful. What follows is a description that concerns intensity-based methods and the types of applications to which they apply. The emphasis of the present work is the advantage for situations demanding a wide range and rapidly varying temperatures.
Date: March 1, 1998
Creator: Allison, S.W.; Beshears, D.L.; Cates, M.R. & Gillies, G.T.
Partner: UNT Libraries Government Documents Department

Dynamic Fiber Optic Sensors Under Intense Radioactive Environments

Description: A liquid mercury target will be used as the neutron source for the proposed Spallation Neutron Source facility. This target is subjected to bombardment by short-pulse, high-energy proton beams. The intense thermal loads caused by interaction of the pulsed proton beam with the mercury create an enormous rate of temperature rise ({approximately}10{sup 7} K/s) during a very brief beam pulse ({approximately } 0.5 {micro}s). The resulting pressure waves in the mercury will interact with the walls of the mercury target and may lead to large stresses. To gain confidence in the mercury target design concept and to benchmark the computer design codes, we tested various electrical and optical sensors for measuring the transient strains on the walls of a mercury container and the pressures in the mercury. The sensors were attached on several sample mercury targets that were tested at various beam facilities: Oak Ridge Electron Linear Accelerator, Los Alamos Neutron Science Center-Weapons Neutron Research, and Brookhaven National Laboratory's Alternating Gradient Synchrotron. The effects of intense background radiation on measured signals for each sensor are described and discussed. Preliminary results of limited tests at these facilities indicate that the fiber optic sensors function well in this intense radiation environment, whereas conventional electrical sensors are dysfunctional.
Date: October 15, 1998
Creator: Allison, S.W.; Earl, D.D.; Haines, J.R. & Tsai, C.C.
Partner: UNT Libraries Government Documents Department

Sensing applications of rare-earth doped luminescent materials

Description: We are developing sensing techniques using phosphors and luminescing crystals. While their use in temperature sensing is becoming well known, there exists the potential to exploit them for other diagnostics. Examples are stress/strain, heat flux, skin friction, pressure, laser-beam profiling, aerodynamic flow, and radiation. We describe our recent results in these areas. 16 refs., 7 figs.
Date: January 1, 1988
Creator: Allison, S.W.; Cates, M.R.; Simpson, M.L.; Noel, B.W.; Turley, D. & Gillies, G.T.
Partner: UNT Libraries Government Documents Department

Proposed method for remote thermometry in turbine engines. [Eu-doped yttrium oxide]

Description: The method uses laser-induced fluorescence from a pulsed uv laser to excite a rare-earth-oxide phosphor bonded in a thin layer to the surface to be measured. The luminescent decay times of certain lines are temperature-dependent. Initial results indicate that at least one phosphor, europium-doped yttrium oxide, is usable to 950/sup 0/C. (DLC)
Date: January 1, 1985
Creator: Noel, B.W.; Cates, M.R.; Allison, S.W.; Borella, H.M.; Franks, L.A. & Marshall, B.R.
Partner: UNT Libraries Government Documents Department

Generalized fast feedback system in the SLC

Description: A generalized fast feedback system has been developed to stabilize beams at various locations in the SLC. The system is designed to perform measurements and change actuator settings to control beam states such as position, angle and energy on a pulse to pulse basis. The software design is based on the state space formalism of digital control theory. The system is database-driven, facilitating the addition of new loops without requiring additional software. A communications system, KISNet, provides fast communications links between microprocessors for feedback loops which involve multiple micros. Feedback loops have been installed in seventeen locations throughout the SLC and have proven to be invaluable in stabilizing the machine.
Date: November 1, 1991
Creator: Hendrickson, L.; Allison, S.; Gromme, T.; Himel, T.; Krauter, K.; Rouse, F. et al.
Partner: UNT Libraries Government Documents Department

Electron Bunch Length Measurement for LCLS at SLAC

Description: At Stanford Linear Accelerator Center (SLAC) a Bunch Length Measurement system has been developed to measure the length of the electron bunch for its new Linac Coherent Light Source (LCLS). This destructive measurement uses a transverse-mounted RF deflector (TCAV) to vertically streak the electron beam and an image taken with an insertable screen and a camera. The device control software was implemented with the Experimental Physics and Industrial Control System (EPICS) toolkit. The analysis software was implemented in Matlab{trademark} using the EPICS/Channel Access Interface for Scilab{trademark} and Matlab{trademark} (labCA). This architecture allowed engineers and physicists to develop and integrate their control and analysis without duplication of effort.
Date: October 4, 2007
Creator: Zelazny, M.; Allison, S.; Chevtsov, Sergei; Emma, P.; Kotturi, K.d.; Loos, H. et al.
Partner: UNT Libraries Government Documents Department

Fast feedback for linear colliders

Description: A fast feedback system provides beam stabilization for the SLC. As the SLC is in some sense a prototype for future linear colliders, this system may be a prototype for future feedbacks. The SLC provides a good base of experience for feedback requirements and capabilities as well as a testing ground for performance characteristics. The feedback system controls a wide variety of machine parameters throughout the SLC and associated experiments, including regulation of beam position, angle, energy, intensity and timing parameters. The design and applications of the system are described, in addition to results of recent performance studies.
Date: May 1, 1995
Creator: Hendrickson, L.; Adolphsen, C.; Allison, S.; Gromme, T.; Grossberg, P.; Himel, T. et al.
Partner: UNT Libraries Government Documents Department

Commissioning experience with the PEP-II low-level RF system

Description: The low-level RF system for PEP-II is a modular design housed in a VXI environment and supported by EPICS. All signal processing and control is done at baseband using in-phase and quadrature (IQ) techniques. Remotely configurable RF feedback loops are used to control coupled-bunch instabilities driven by the accelerating mode of the RF cavities. A programmable DSP based feedback loop is implemented to control phase variations across the klystron due to the required adjustment of the cathode voltage to limit cathode power dissipation. The DSP loop also adaptively cancels modulations caused by klystron power supply ripple at selected power line harmonics between 60 Hz and 10 kHz. The system contains a built-in baseband network analyzer which allows remote measurement of the RF feedback loop transfer functions and automated configuration of these loops. This paper presents observations and measured data from the system.
Date: May 1, 1997
Creator: Corredoura, P.; Allison, S.; Claus, R.; Ross, W.; Sapozhnikov, L.; Schwarz, H.D. et al.
Partner: UNT Libraries Government Documents Department