@inproceedings{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Eutektische Hochtemperatur-Fixpunkte f{\"u}r die Dynamische Differenzkalorimetrie}, publisher = {Sensoren und Messsysteme 2010 - 15. ITG/GMA-Fachtagung}, abstract = {Eutektische Metall-Kohlenstoff-(M-C)-Fixpunkte erweitern den Temperaturbereich in dem Hochtemperaturfixpunkte eingesetzt werden k{\"o}nnen vom h{\"o}chsten Temperaturfixpunkt der derzeit g{\"u}ltigen Internationalen Temperaturskala von 1990 (ITS-90) der Erstarrungstemperatur von Kupfer bei 1357.77 K bis hin zu Temperaturen von bis zu 3500 K. Bislang sind diese Hochtemperaturfixpunkte ausschließlich eingesetzt worden, um die Kalibrierung von Strahlungsthermometern und Thermoelementen zu vereinfachen. Herk{\"o}mmlicherweise ist das Fixpunktmaterial dabei in einem Graphittiegel, in den ein Hohlraumzylinder eintaucht, gefasst. Der Hohlraumzylinder dient dabei als Schwarzk{\"o}rper f{\"u}r ein Strahlungsthermometer und als Tauchrohr f{\"u}r Anwendungen in der Ber{\"u}hrungsthermometrie. Oberhalb von 1300 K w{\"u}rde auch die Messung thermophysikalischer Eigenschaften, d.h. Methoden der thermischen Analyse wie die dynamische Differenzkalorimetrie (DSC), die Laserflash-Methode oder die Dilatometrie, signifikant von der in-situ Anwendung der eutektischen Metallkohlenstoff-Fixpunkte profitieren. Der Beitrag pr{\"a}sentiert die Entwicklung und Untersuchung von Metallkohlenstoff-Hochtemperaturfixpunkten f{\"u}r die Anwendung in DSC Messapparaturen im Temperaturbereich bis 2300 K. Im Gegensatz zu der etablierten Anwendung in Strahlungsthemometrie und Ber{\"u}hrungsthemometrie sind die Materialmengen, die f{\"u}r eine Temperaturkalibrierung ben{\"o}tigt werden, in der thermischen Analyse mit einigen Milligramm Fixpunktmaterial sehr gering. Spezielle Verfahren wurden dabei f{\"u}r die effektive Pr{\"a}paration solch kleiner, und f{\"u}r den Einsatz als Temperaturfixpunkt hochreiner, Probenmassen entwickelt.}, language = {de} } @inproceedings{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Optische Hochtemperaturmesstechnik f{\"u}r die Thermometrie, Radiometrie und Photometrie}, publisher = {Sensoren und Messsysteme 2010 - 15. ITG/GMA-Fachtagung}, abstract = {Die Temperaturmessung {\"u}ber die emittierte W{\"a}rmestrahlung ist seit {\"u}ber hundert Jahren ein innovatives Feld der Messtechnik und der Grundlagenphysik. Ein erster H{\"o}hepunkt war Gustav Kirchhoffs theoretisches Prinzip eines Schwarzen K{\"o}rpers mit idealen - von Material und Form unabh{\"a}ngigen - Emissionseigenschaften f{\"u}r W{\"a}rmestrahlung. Diese fr{\"u}hen Entwicklungen gipfelten in Max Planck's ber{\"u}hmtem Strahlungsgesetz, das die Emission von W{\"a}rmestrahlung exakt beschreibt und den Beginn der modernen Quantenphysik einleitet. Die quantitative Messung von W{\"a}rmestrahlung erfordert die Kenntnis von Quellen- und Detektoreigenschaften. Im Bereich der Erzeugung von W{\"a}rmestrahlung werden noch heute die gleichen Prinzipien benutzt wie zu Zeiten Plancks, d. h. es werden technologisch weiter entwickelte Hohlraumstrahler zur Realisierung Schwarzer K{\"o}rper eingesetzt. Im Bereich der Detektion von W{\"a}rmestrahlung haben sich jedoch durch die Entwicklung der Halbleitertechnik grunds{\"a}tzlich andere physikalische Prinzipien durchgesetzt. W{\"a}hrend zu Plancks Zeiten thermische Empf{\"a}nger eingesetzt wurden, finden im Hochtemperaturbereich heute - neben thermischen Empf{\"a}ngern - fast ausschließlich photoelektrische Empf{\"a}nger Anwendung. Einen weiteren entscheidenden Schritt in Richtung h{\"o}chster Genauigkeit bedeutete die Entwicklung eines elektrischen Substitutionsradiometers bei sehr tiefen Temperaturen, des so genannten Kryoradiometers. Die Erfindung des Kryoradiometers als prim{\"a}rer Detektorstandard Ende der 1970er Jahre erm{\"o}glichte die Messung optischer Strahlungsleistung mit einer relativen Unsicherheit von unter 10-4. Basierend auf diese Strahlungsleistungsmessung ist heute die Kalibrierung der spektrale Empfindlichkeit von Detektoren mit relativen Unsicherheiten bis zu 10-4 m{\"o}glich. Moderne Halbleiterempf{\"a}nger liefern einen strahlungsleistungsproportionalen Photostrom. Zur Messung der W{\"a}rmestrahlung {\"u}ber einen weiten Temperatur- und Wellenl{\"a}ngenbereich m{\"u}ssen Photostr{\"o}me von fA bis mA mit kleinster Unsicherheit bestimmt werden. Das stellt hohe experimentelle Anforderungen an die elektrische, geometrische und optische Messtechnik. Der Beitrag beschreibt kurz die historische Entwicklung der optischen Temperaturmessung {\"u}ber die ausgesandte W{\"a}rmestrahlung und geht dann auf die experimentellen und physikalischen Grundlagen dieser Methode ein. Abschließend werden M{\"o}glichkeiten zur Implementierung der im Metrologielabor erreichbaren niedrigen Messunsicherheiten in den praktischen messtechnischen Alltag vorgestellt.}, language = {de} } @inproceedings{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Progress with the development of high temperature fixed-points in the EU through the Himert project}, pages = {6}, abstract = {The EU FP5 funded research project HIMERT (Novel High temperature Metal-carbon Eutectic fixed points for Radiation Thermometry, Radiometry and Thermocouples) aims to develop high temperature fixed points above the freezing point of copper to approximately 2500 deg C with a repeatability of less than 0.1 deg C. NPL and BNM-INM have constructed fixed-point blackbody sources, while BNM-LNE has constructed cells up to 1950 deg C (Ru-C) for the calibration of contact sensors. PTB will perform absolute radiometry of the cells constructed by NPL and BNM-INM. Pt-Pd thermocouple studies will be undertaken by PTB and BNM-LNE. Also a major materials compatibility study has been undertaken by BNM-LNE to identify thermocouple sheath materials that are compatible with graphite to 1950 deg C. The University of Valladolid is investigating the background physics of the eutectic process and seeking to develop physically realistic models. The two industrial companies will test whether improved traceability at lower uncertainties can be achieved by using metal-carbon eutectics. This paper describes the HIMERT project and current progress. (authors)}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {A novel lens free high-accuracy InGaAs radiation thermometer for radiation temperatures above 300°C}, series = {VDI Berichte (1784)}, journal = {VDI Berichte (1784)}, pages = {155 -- 162}, abstract = {A novel high-accuracy radiation thermometer designed for laboratory applications and based on an InGaAs photon detector is presented. In contrast to other radiation thermometers, no imaging optics is used for collecting the radiation. By using a set of two equally sized optical apertures at fixed distances from the detector and a short distance of the thermometer from the radiation source, the size-of-source effect of the instrument is minimized. The radiation thermometer is designed for temperature measurements from 300°C upwards. Technical details of the radiation thermometer together with the measured reference function according to the ITS-90 up to 962°C and its temporal stability are presented. The size-of-source effect of the novel lens-free radiation thermometer is compared with the lens-based InGaAs reference radiation thermometer of the Physikalisch-Technische Bundesanstalt.}, language = {en} } @inproceedings{HartmannManaraZipfetal., author = {Hartmann, J{\"u}rgen and Manara, Jochen and Zipf, Matthias and Stark, Thomas and Arduini, Mariacarla and Ebert, Hans-Peter and Tutschke, Andreas and Hallam, Andrew and Hanspal, Jagdevinder and Langley, Mark}, title = {Development and validation of a long wavelength infrared (LWIR) radiation thermometer for contactless temperature measurements in gas turbines during operation}, series = {EVI-GTI and PIWG Joint Conference on Gas Turbine Instrumentation}, booktitle = {EVI-GTI and PIWG Joint Conference on Gas Turbine Instrumentation}, publisher = {IET}, pages = {1 -- 26}, abstract = {A collection of slides from the author's conference presentation is given. The presentation introduces the infrared-optical characterization of thermal barrier coatings and the development of LWIR pyrometer for measuring temperature in an operating gas turbine. The test facility for evaluating the LWIR pyrometer is also presented. This presentation includes the experimental setup for LWIR calibration and measurement.}, language = {en} } @inproceedings{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {The PriTeRa facility of PTB for spectral radiance and irradiance calibrations and radiation thermometry in the range from {\`A}170 C up to 3200 C and from 200 nm up to 50 μm}, series = {Proc. Newrad}, booktitle = {Proc. Newrad}, pages = {13 -- 16}, abstract = {Blackbody radiators provide calculable spectral radiance and irradiance if their temperature and their emissivity is well known. Due to technical restrictions, one single blackbody can cover only a limited temperature range and therefore limited wavelengths for spectral radiance and irradiance calibrations. Space borne instruments for measuring the solar emission usually need calibrations from the UV to the near Infrared part of the optical spectrum [1] whereas remote sensing experiments for measuring earth surface temperatures for climate prediction or spaceborne instruments that deliver evidence for water on the surface of planet Mars [2] require calibration in the far infrared spectral range. To achieve these complementary requirements, PTB has set-up a series of blackbody based instrumentations, which are combined in the Primary Temperature Radiator facility (PriTeRa). To cover the whole wavelength range from 200 nm up to 800 µm different blackbody designs have to be applied.}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {The composition analysis of YBa2Cu3O7-δ or PrBa2Cu3O7-δ thin films and (YBa2Cu3O7-δ/PrBa2Cu3O7-δ) n heterostructures prepared by CVD}, series = {Fresenius' journal of analytical chemistry}, volume = {357}, journal = {Fresenius' journal of analytical chemistry}, number = {8}, pages = {1061 -- 1065}, abstract = {Some YBa2Cu3O7-δ films and heterostructures prepared by Chemical Vapor Deposition (CVD) were analyzed in our laboratories by EPMA-EDX or WDX, RBS, SNMS and AES. It was found that in some cases the results of composition analysis can significantly deviate from each other. At least two main reasons for these deviations exist: the different lateral resolution and the application of different reference samples for the calibration.}, language = {en} } @techreport{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Improvement of the active layers of a field effect sensor for fluorine}, organization = {6. international meeting on chemical sensors, Gaithersburg, MD (United States)}, pages = {313}, abstract = {The quantitative determination of fluorine in gases is of great importance as this gas is often used in various industrial processes, but is toxic even at low concentrations. Therefore, there is a great demand for sensors for this gases and alarm systems controlling the environment. Recently, the auhtors reported on first results with a new field effect sensor for the determination of F {sub 2}. A silicon substrate was used with a thin layer of LaF {sub 3} in direct contact to the semiconductor and platinum electrode on the top. In early results, a good sensitivity was achieved but an insufficient stability and limit of detection required further improvements. The corresponding findings and fundamental investigations on the sensor mechanism will be given in this paper.}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Thermal resistance of thermal barriers in polycrystalline diamond}, series = {Progress in Natural Science}, journal = {Progress in Natural Science}, number = {6}, pages = {297}, abstract = {Micrometer resolved photoțhermal measurements on chemical vapour deposited (CVD) diamond are presented. It is shown that the thermal conductivity inside the grains is as high as that of natural IIa diamond. Using two different approaches we measure the thermal resistance of thermal barriers like grain boundaries or microcracks and obtain values of the order of 10" m'Kw. A simple model is presented, relating the overall thermal conductivity for one-dimensional heat flow to the thermal resistance at barriers and the average size of the grains. Good agreernent between predictions and literature data is found, ...}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Development and test of a long wavelength infrared radiation thermometer for non-contact temperature measurements in gas turbines during operation}, series = {Technisches Messen}, volume = {85}, journal = {Technisches Messen}, number = {1}, pages = {28 -- 39}, abstract = {The aim of this work was the development of a long wavelength infrared radiation thermometer for the non-contact measurement of surface temperatures in stationary gas turbines during operation within the EU-project, Sensors Towards Advanced Monitoring and Control of Gas Turbine Engines (acronym STARGATE)". In this work, the infrared-optical properties of the thermal barrier coatings and the combustion gases were determined at ZAE Bayern at high temperatures up to 1600 K and pressures up to 13 bar. Based on these experimental characterizations, a suitable spectral range could be identified which lies around 10 mu m for the long-wavelength infrared radiation thermometer. According to these findings, a laboratory setup with suitable optical components (filters, IR-fibers, etc.) was firstly realized and verified. Subsequently, a prototype for measurements in gas turbines during operation of the turbines has …}, language = {en} } @inproceedings{HartmannHarrerDotterweichetal., author = {Hartmann, J{\"u}rgen and Harrer, S. and Dotterweich, C. and Zink, Markus H. and Hemberger, Frank and Ebert, Hans-Peter and Schnitzler, Tim}, title = {Phase change materials for use in thermally and electrically stressed insulation for high voltage applications}, series = {2016 IEEE Electrical Insulation Conference}, booktitle = {2016 IEEE Electrical Insulation Conference}, publisher = {IEEE}, isbn = {978-1-4673-8706-4}, pages = {605 -- 608}, abstract = {The temperature of high voltage equipment is often the limiting factor when transmitting electrical energy because the electrical insulation can get severely aged when the temperature is exceeding a certain limit. Hence, cooling has to be improved or heat generation must be reduced to avoid damage of the insulation. In this paper a new method was examined by investigating electrically insulating phase change materials which are able to store latent heat during a phase change from the solid to liquid state in times of high energy demand. To verify the electrically insulating properties of paraffins, one class of phase change materials, a special test cell was designed allowing the determination of breakdown voltage of phase change materials. The measurements on one paraffin sample proved the promising electrical insulating properties and it was shown that the breakdown voltage in the liquid state is comparable …}, language = {en} } @inproceedings{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {I3. 4-Radiometric calibration of the NIRSpec instrument on the James Webb Space Telescope in the wavelength range from 0.7 μm to 5.0 μm}, series = {SENSOR+TEST Conference 2009 - IRS² 2009 Proceedings}, booktitle = {SENSOR+TEST Conference 2009 - IRS² 2009 Proceedings}, pages = {249 -- 254}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Strahlungsthermometrie}, series = {PTB-Mitteilungen 117}, volume = {117}, journal = {PTB-Mitteilungen 117}, number = {3}, pages = {272 -- 281}, abstract = {Der prinzipielle Aufbau eines Strahlungsthermometers ist in Bild 2 dargestellt. Eine Optik bildet das Messobjekt mittels der W{\"a}rmestrahlung auf die Gesichtsfeldblende vor dem Detektor ab. Die Aperturblende und die Gesichtsfeldblende definieren den Raumwinkel und die Fl{\"a}che (Messfeld) der vom Detektor nachgewiesenen Strahlung. Bei den meisten Strahlungsthermometern wird ein Spektralfilter zur Eingrenzung des Wellenl{\"a}ngenbereiches der auf den Detektor treffenden Strahlung verwendet. Dieser Spektralfilter wird oft unmittelbar vor dem Detektor angeordnet oder ist als Fenster in das Detektorgeh{\"a}use integriert. Bei hochwertigen Strahlungsthermometern wird der Detektor und manchmal auch zus{\"a}tzlich der Spektralfilter temperiert. Interne Referenzstrahlungsquellen oder nur die Messung und Verarbeitung der internen Temperatur des Detektors oder der optischen Komponenten sorgen im allgemeinen f{\"u}r eine stabile Anzeige von Messwerten der Strahlungstemperatur innerhalb eines weiten Eigentemperaturbereichs des Strahlungsthermometers. Die Leistungsf{\"a}higkeit eines Strahlungsthermometers wird wesentlich von der G{\"u}te seiner Optik und der Empfindlichkeit seines Strahlungsempf{\"a}ngers bestimmt. Hochwertige Strahlungsthermometer arbeiten mit einem festen Fokus, der dem empfohlenen Messabstand entspricht, oder mit variablem Fokus zur Anpassung an den Messabstand. Aus der abstandsabh{\"a}ngigen Einstellung des Fokus resultiert ein Messfeld, in dem die mittlere Strahlungstemperatur des Messobjektes ermittelt wird. Genaue Messungen der Strahlungstemperatur sollten mit abbildenden optischen Systemen erfolgen …}, language = {de} } @inproceedings{HartmannTaubertMonteetal., author = {Hartmann, J{\"u}rgen and Taubert, Dieter Richard and Monte, C. and Gutschwager, B. and Hollandt, J{\"o}rg}, title = {Traceable calibration of radiation sources from the visible to the far infrared for space borne applications at PTB}, series = {Proceedings of SPIE Volume 7474, Sensors, Systems, and Next-Generation Satellites XIII}, booktitle = {Proceedings of SPIE Volume 7474, Sensors, Systems, and Next-Generation Satellites XIII}, abstract = {The Physikalisch-Technische Bundesanstalt (PTB) has developed dedicated instrumentations and methods for the traceable calibration of space borne instruments in terms of the three fundamental radiometric units, i.e. spectral radiance (radiation temperature), spectral radiant intensity and spectral photon flux. The traceable calibration under conditions similar to the space environment is achieved by use of two major radiometric calibration facilities of PTB, the Spectral Radiance Comparator Facility (SRCF) and the Reduced Background Calibration Facility (RBCF) which are part of the Primary Temperature Radiator Facility of PTB and cover the wavelength range from the UV to the FIR (THz range). The improved detector instrumentations of the SRCF and RBCF, detailed calibration schemes and results of calibrations for space missions are presented.}, language = {en} } @inproceedings{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Long term stability of the spectral responsivity of filter radiometers at the PTB}, series = {Proc. of TEMPMEKO}, booktitle = {Proc. of TEMPMEKO}, editor = {Zvizdic, D.}, pages = {977 -- 982}, abstract = {The Physikalisch-Technische Bundesanstalt (PTB) uses calibrated filter radiometers to measure the thermodynamic temperature of blackbodies applied for the realisation and dissemination of the spectral radiance and spectral irradiance. This paper presents the PTB experience with the stability of the spectral responsivities of two different sets of filter radiometers, a set of four broad-band filter radiometers with centroid wavelengths in the visible spectral range (437 nm, 510 nm, 558 nm and 728 nm), using a combination of coloured glass filters as wavelength selective elements and a set of five narrow-band interference filter radiometers with centroid wavelengths in the visible and in the near infrared wavelength range (676 nm, 802 nm, 903 nm and 1003 nm). The time period of their continuous investigation with respect to the relevant stability parameters, the integrated spectral responsivity and the centroid wavelength, is about seven years for the broad-band filter radiometers and up to ten years for the narrow-band interference filter radiometers. Both types of filter radiometers show sufficient stability for their application as high-accuracy temperature measurement instruments. Relative changes in the integrated spectral responsivity up to some parts in 103 and for the interference filter radiometers a linear increase of the centroid wavelength with time in the order of several ten picometers per year have been observed. A comparison between the two types of filter radiometers is given, with respect to the contribution of the stability of these parameters to the uncertainty budget of thermodynamic temperature determination. Reasons for the observed …}, language = {en} } @inproceedings{HartmannMcEvoyMachinetal., author = {Hartmann, J{\"u}rgen and McEvoy, H.C. and Machin, Graham and Friedrich, R. and Hollandt, J{\"o}rg}, title = {Comparison of the New NPL Primary Standard Ag Fixed-Point Blackbody Source with the Primary Standard Fixed Point of PTB}, series = {AIP Conference Proceedings (684)}, booktitle = {AIP Conference Proceedings (684)}, publisher = {American Institute of Physics}, isbn = {0-7354-0153-5}, pages = {909 -- 914}, abstract = {Above the freezing point of silver (961.78 °C), the International Temperature Scale of 1990 is defined in terms of Planck's radiation law. The scale is maintained and disseminated using a validated and linear pyrometer in conjunction with a blackbody reference source at either the Ag, Au (1064.18 °C) or Cu (1084.62 °C) freezing point. In order to realize the scale with the highest precision high quality, well-characterised, reproducible fixed-point blackbody sources are required. Such sources have been maintained at NPL for a number of years, but it was felt that improvements to the design would be beneficial. A new Ag point blackbody source has therefore been constructed. The new design will improve the quality and reproducibility of the melting and freezing plateaux and reduce errors due to the 'out-of-focus' size-of-source effect which is difficult to measure and to eliminate. Full details of the design of the new …}, language = {en} } @inproceedings{HartmannTaubert, author = {Hartmann, J{\"u}rgen and Taubert, Dieter Richard}, title = {Assessing blackbody emissivity by monte carlo simulation}, series = {Proc. of the Int. Conference of Infrared Sensors and Systems}, booktitle = {Proc. of the Int. Conference of Infrared Sensors and Systems}, publisher = {AMA Service GmbH}, pages = {133 -- 138}, language = {en} } @inproceedings{HartmannFischer, author = {Hartmann, J{\"u}rgen and Fischer, Joachim}, title = {Radiator standards for accurate IR calibrations in remote sensing based on heatpipe blackbodies}, series = {Proceedings Volume 3821, Environmental Sensing and Applications}, booktitle = {Proceedings Volume 3821, Environmental Sensing and Applications}, number = {3821}, editor = {Carleer, M. and Hilton, M. and Lamp, T. and Reuter, R. and Russwurm, G.M. and Schaefer, K. and Weber, K. and Weitkamp, K. and Wolf, J. and Woppowa, L.}, publisher = {International Society for Optics and Photonics - Proceedings of SPIE}, pages = {395 -- 403}, abstract = {The demand of instrumentation in the field of remote sensing is increasing rapidly. For international compatibility, for reliable results and precise long-term investigation, necessary for example in the measurement of climatic trends, accurate traceability of the results to international standards or SI-units is mandatory. Additionally, interpretation of the results strongly requires a careful evaluation of the involved errors and the resulting uncertainties in order to allow for a rating of the obtained results. For that purpose quality assurance was introduced, not only for industrial fabrication, but also, and with increasing tendency, for industrial and scientific research. As an overview, the necessity and the possibilities of quality assurance in the area of remote sensing are discussed. Taking remote sensing of temperature as an example, the general approach is described. For that purpose, a description of heatpipe blackbodies …}, language = {en} } @inproceedings{HartmannFischer, author = {Hartmann, J{\"u}rgen and Fischer, Joachim}, title = {Calibration of tungsten strip lamps as transfer standards for temperature}, series = {Proceedings of TEMPMEKO (99)}, booktitle = {Proceedings of TEMPMEKO (99)}, editor = {Dubbeldam, J.F. and de Groot, M.J.}, publisher = {IMEKO}, address = {Delft}, pages = {561 -- 566}, abstract = {An advanced method for the calibration of tungsten strip lamps is reviewed in detail. The method is based on measuring the ratio of the spectral radiances of two sources at different radiance temperatures TL by radiation thermometry. Instead of using the distribution temperature and the colour emissivity for the calculation of the radiance temperature, the derivative dTL/dλ in the vicinity of the effective wavelength of the detection system is applied. In a first step high-stability vacuum tungsten strip lamps are calibrated as first-order working standards with respect to fixed points of the International Temperature Scale of 1990 (ITS-90). In a subsequent step, secondary working standards are calibrated relative to these first order working standards with light of different wavelengths determined by interference filters. A detailed description of the evaluation procedure for the determination of the radiance temperature of the lamps is given and several problems encountered in operating the lamps are discussed. The standard uncertainties of the radiance temperature are below 0.2 K for the first order working standards.}, language = {en} } @article{HartmannAnhaltHollandtetal., author = {Hartmann, J{\"u}rgen and Anhalt, Klaus and Hollandt, J{\"o}rg and Schreiber, Ekkehard and Yamada, Y.}, title = {Improved thermal stability of the linear pyrometer LP3 for high temperature measurements within the EU-project Himert}, series = {VDI Bericht 1784}, journal = {VDI Bericht 1784}, pages = {135 -- 141}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Realisation and dissemination of thermodynamic temperature above 1234.93 K}, series = {CCT Working Documents}, journal = {CCT Working Documents}, language = {en} }