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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

Turbine-engine applications of thermographic-phosphor temperature measurements

Description: The thermographic-phosphor (TP) method can measure temperature, heat flux, strain, and other physical quantities remotely in hostile and/or inaccessible environments such as the first-stage turbine components in turbine engines. It is especially useful in situations in which no other known method works well. This paper is a brief review of engine tests that demonstrated the utility of the TP method. For the most part, the results presented here are discussed only qualitatively. The papers in the bibliography describe these and other experiments and results in detail. The first viewgraph summarizes the many desirable features of the TP method. The second viewgraph describes TPs, and the third summarizes how the TP method works. To measure single-point temperatures in turbine-engine applications, we use the decay-time method, which depends on the fact that the luminescence following an impulse of ultraviolet excitation decays, with a characteristic decay time that. Is a monotonically decreasing function of temperature over some range of temperatures. The viewgraph is a set of calibration curves showing the behavior of some useful emission lines for ten important TPs. Consider Lu PO{sub 4}:Eu as an example. Below the {open_quotes}quenching{close_quotes} temperature near 900 Y, the decay time is nearly constant. Above it, the decay time decreases exponentially with the temperature. This strong functional dependence means that one can have a fairly large error in the lifetime measurement, as in environments with poor signal-to-noise ratios (SNRs), yet still obtain high accuracy in the temperature measurement. Our more-recent data up to 1900 K show the same behavior.
Date: December 31, 1995
Creator: Noel, B. W.; Turley, W. D. & 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 absorption and emission properties of eight phosphorescent compounds. These phosphors are commercially produced powders that emit mainly in the blue region when illuminated with ultraviolet light in the range 220 to 400 mn. Excitation and emission spectra measured over the range 20 to 350{degrees}C are examined for these phosphors. Data from the emission spectra indicate that there is a significant temperature dependence in this temperature range. In all eight phosphors, the maximum relative intensity decreased as the temperature increased. In some samples, the emission bandwidth and position 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 studies at higher temperatures.
Date: May 1, 1993
Creator: Cunningham, D. M.; Allison, S. W. & Smith, D. B.
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

Thermographic-phosphor temperature measurements: Commercial and defense-related applications

Description: This paper is a review of a diverse set of applications of the thermographic-phosphor (TP) method for measuring temperatures remotely. The TP method is useful in hostile and/or inaccessible environments where no other known method works. It is highly accurate, nonintrusive, durable, conceptually simple, covers an unprecedented temperature range (0 K to >1200 K), can measure temperature at a single point or over an entire surface, and can make static, steady-state, or very high speed dynamic measurements. The TP method can also be used to make leadless, remotely interrogated heat-flux gauges that can nonintrusively measure spatial distributions of heat flux over arbitrarily large areas with high resolution. The applications described include measurements in gas centrifuges, motors, variable-area ejectors, rotors and stators in gas turbines, and others. The authors also briefly discuss heat-flux gauges and their applications.
Date: June 1, 1994
Creator: Noel, B. W.; Turley, W. D. & Allison, S. W.
Partner: UNT Libraries Government Documents Department

Adaptive cascaded beam-based feedback at the SLC

Description: The SLAC Linear Collider now has a total of twenty-four beam-steering feedback loops used to keep the electron and positron beams on their desired trajectories. Seven of these loops measure and control the same beam as it proceeds down the linac through the arcs to the final focus. Ideally each loop should correct only for disturbances that occur between it and the immediate upstream loop. In fact, in the original system each loop corrected for all upstream disturbances. This resulted in undesirable over-correction and ringing. We added MIMO (Multiple Input Multiple Output) adaptive noise cancellers to separate the signal we wish to correct from disturbances further up-stream. This adaptive control improved performance in the 1992 run.
Date: May 1, 1993
Creator: Himel, T.; Allison, S.; Grossberg, P.; Hendrickson, L.; Sass, R. & Shoaee, H.
Partner: UNT Libraries Government Documents Department

An adaptive noise cancelling system used for beam control at the Stanford Linear Accelerator Center

Description: The SLAC Linear Collider now has a total of twenty-four beam-steering feedback loops used to keep the electron and positron beams on their desired trajectories. Seven of these loops measure and control the same beam as it proceeds down the linac through the arcs to the final focus. Ideally by each loop should correct only for disturbances that occur between it and the immediate upstream loop. In fact, in the original system each loop corrected for all upstream disturbances. This resulted in undesirable over-correction and ringing. We added MIMO (Multiple Input Multiple Output) adaptive noise cancellers to separate the signal we wish to correct from disturbances further upstream. This adaptive control improved performance in the 1992 run.
Date: June 1, 1993
Creator: Himel, T.; Allison, S.; Grossberg, P.; Hendrickson, L.; Sass, R. & Shoaee, H.
Partner: UNT Libraries Government Documents Department

MPS Vax monitor and control software architecture

Description: The new Machine Protection System (MPS) now being tested at the SLAC Linear Collider (SLC) includes monitoring and controlling facilities integrated into the existing VAX control system. The actual machine protection is performed by VME micros which control the beam repetition rate on a pulse-by-pulse basis based on measurements from fault detectors. The VAX is used to control and configure the VME micros, configure custom CAMAC modules providing the fault detector inputs, monitor and report faults and system errors, update the SLC database, and interface with the user. The design goals of the VAX software include a database-driven system to allow configuration changes without code changes, use of a standard TCP/IP-based message service for communication, use of existing SLCNET micros for CAMAC configuration, security and verification features to prevent unauthorized access, error and alarm logging and display updates as quickly as possible, and use of touch panels and X-windows displays for the user interface.
Date: April 1, 1993
Creator: Allison, S.; Spencer, N.; Underwood, K.; VanOlst, D. & Zelanzy, M.
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