Resolved Temperature Measurements Research Articles

Temperature measurements along a vertical borehole heat exchanger: A method comparison

The standard thermal response tests (TRT) provide integral and effective thermal parameters of the ground in the vicinity of borehole heat exchangers (BHE). However, typical ground properties are heterogeneously distributed. As a result, advanced TRT such as distributed and enhanced TRT are growing in popularity as they provide more spatial information of the thermal properties. Thus, the objective of this study is to compare various instruments to measure the depth-dependent temperatures using standard Pt100-sensors, fiber optical thermometers and novel instruments such as Geowire, Geoball and GEOsniff®. The investigations are carried out in a 30 m length test borehole. The results showed an excellent agreement between both the Geowire and GEOsniff® in comparison with Pt100-sensors with a root mean squared error of 0.10 and 0.09 K, respectively. The results also suggest that the novel instruments have various advantages over the standard sensors and fiber optics. For example, with the novel instruments comparable, accurate, inexpensive, instantaneous and higher spatial resolution temperature measurements are obtained. Finally, the outcome of this study provides a guide for choosing the adequate temperature measurement along a BHE thus generally improving the evaluation of advanced TRT, while potentially increasing efficiency and economic viability of ground-source heat pump systems.

Improvements in the design of thermal-infrared radiation thermometers and sensors.

A new design for thermal-infrared radiation thermometer and sensors is described. Critical optical elements, such as the field stop, Lyot stop, collimating lens, and detector, are placed inside a thermally stabilized assembly that is controlled using thermo-electric coolers and thermistors. The assembled radiation thermometer is calibrated using both variable-temperature fluid-bath and heat-pipe blackbodies from -45 °C to 75 °C and the use of a modified-Planck function and these blackbodies. The size-of-source effect both with and without the Lyot stop has been measured. This new design, during operations without the need for cryogenic cooling, demonstrates sub millikelvin temperature measurement resolution with few millikelvin, week-long stable operations while measuring room-temperature objects.

Frequency-modulated continuous-wave laser interferometric optical fiber temperature sensor

This paper presents an extrinsic Fabry-Perot (F-P) cavity optical fiber temperature sensor, which is based on the frequency-modulated continuous-wave laser interference. The temperature sensing probe is fabricated by a stainless-steel tube with high coefficient of thermal expansion to encapsulate the F-P cavity. Stainless steel tube is used as the F-P cavity and also the temperature sensitive component. The variation of cavity length caused by thermal expansion of F-P cavity is measured by frequency-modulated continuous-wave interferometric measurement technique. The experimental results show that the temperature measurement resolution of the fiber temperature sensor reached 0.0002 ℃ and the temperature measurement sensitivity reached 3022 nm/℃. The temperature sensor not only has high sensitivity and resolution, but also has a simple and stable structure and a good application prospect.

The effect of ambient pressure on the heat transfer of a water spray

The present work is aimed at quantifying the effects of ambient pressure in the heat transfer at single injections of a full cone spray over a hot metal surface. The experimental configuration is that of a spray impinging down perpendicularly onto a flat surface located at 55mm inside an injection chamber. The experiments were conducted for prescribed initial wall temperatures ranging from single phase to local nucleate boiling and transition regimes of heat transfer. Ambient pressures ranged from atmospheric to 30bar. The analysis is based on spatial resolved measurements of the instantaneous surface temperature during the injection period. The measurements are then processed in order to obtain estimates of the time-averaged values of the local heat flux. The overall cooling rate is also obtained by integrating the local values within the total area of the spray impact. Results show that the amount of heat extracted by the impinging spray increases 3.4 times when ambient pressure is increased from atmospheric to 20bar at the same superheating degree at the wall of 45°C. This corresponds to an increase from 13.3% to 47.7% in the ratio between the actual cooling and the theoretical maximum cooling, defined here as cooling efficiency. This is a result of a better spreading of the liquid film at the wall, covering a larger footprint upon impact. Instantaneous peak heat flux is also increased, as a clear indication of the improved heat transfer between the impinging droplets and the wall.The work presented herein derives from a broader research program devised to develop a system for in-cylinder cooling of internal combustion engines using high pressure water sprays produced by gasoline direct injectors.

Lidar thermometry using two-line atomic fluorescence.

In this work, Scheimpflug lidar has been combined with the thermometric technique two-line atomic fluorescence, to carry out stand-off, spatially resolved temperature measurements. Indium atoms were seeded into a modified Perkin-Elmer-burner and two tunable single-mode diode lasers with their wavelengths tuned to 410.17 and 451.12 nm were used to excite the seeded atoms. The fluorescence signal was collected using both a line-scan detector and a two-dimensional intensified CCD camera. One-dimensional flame temperature profiles were measured at different heights above a porous-plug burner, located at a distance of 1.5 m from the lidar system. The technique was also used to demonstrate two-dimensional temperature measurements in the same flame. The accuracy of the measured temperature was found to be limited mainly by uncertainty in the spectral overlap between the laser emission and the indium atom absorption spectrum as well as uncertainty in laser power measurements. With the constraint that indium can be introduced into the measurement volume, it is anticipated that the developed measurement concept could constitute a valuable tool, allowing in situ spatially resolved thermometry in intractable industrial applications, sufferings from limited optical access, thus requiring remote single-optical-port sensing.

Experimental investigation of plasma parameters in 13.56 MHz/2 MHz cylindrical inductively coupled plasma

Inductively coupled plasmais widely used in semiconductor and display process because of its desirable characteristics such as high plasma density, simple structure and independently controllable ion energy. The driving frequency is a significant parameter that generates and maintains the plasma. However, the effects of different driving frequencies on the radial distribution of the plasma parameters are hardly investigated. So a large area cylindrical inductively coupled plasma source driven separately by 2 MHz and 13.56 MHz is investigated. In order to perform a comprehensive investigation about the effect of driving frequency, the radially resolved measurements of electron density, electron temperature and density of metastable state atoms for the argon discharge are systematically analyzed by Langmuir double probe and optical emission spectroscopy at various power values and gas pressures. It is found that input power values at high frequency (13.56 MHz) and low frequency (2 MHz) have different effects on plasma parameters. When discharge is driven at high frequency, the electron density increases obviously with the increase of power. However, when discharge is driven at low frequency, the electron temperature increases evidently with the increase of power. This can be explained by calculating the skin depths in high and low frequency discharge. When the discharge is driven at high frequency, the induced electromagnetic field is higher than that at low frequency, and the single electron obtains more energy. It is easier to ionize, so the energy is mainly used to increase the electron density. When the discharge is driven at low frequency, the skin layer is thicker, the number of heated electrons is larger, and the average energy of electrons is increased, so the energy is mainly used to raise the electron temperature. At a gas pressure of 10 Pa, the electron density shows a ‘convex’ distribution and increases with the increase of input power for both the high-frequency and low-frequency discharge. While the distributions of electron temperature are obviously different. When the discharge is driven at high frequency, the electron temperature is relatively flat in the center of the chamber and slightly increases on the edge. When the discharge is driven at low frequency, the electron temperature gradually decreases along the radial position. This is due to the one-step ionization in the high-frequency discharge and the two-step ionization in the low-frequency discharge. In order to prove that the low-frequency discharge is dominated by two-step ionization, the spectral intensities of the argon plasma under the same discharge conditions are diagnosed by optical emission spectroscopy. The number density of metastable states is calculated by the branch ratio method. The results are consistent with the analyses. At a gas pressure of 100 Pa, the electron density increases and then decreases with the increase of radial distance, and the overall distribution shows a " saddle shape” for high frequency and also for low frequency discharge. Although the uniformity of electron density improves with the gas pressure, the uniformity at low frequency is better than that at high frequency. The reason can be attributed to the fact that the skin layer of low frequency is thicker and the heating area is wider.

Feasibility Study for Implementing an Optical Thomson Scattering System for Studying Photoionized Plasmas on Z

Many astrophysical environments such as X-ray binaries, active galactic nuclei, and accretion disks of compact objects have photoionized plasmas. The strong photoionizing environment found near these bright X-ray sources can be produced in a scaled laboratory experiment, and direct measurements can form a testbed for spectroscopic models and photoionization codes used in analysis of these astrophysical objects. Such scaled experiments are currently being conducted using Ne filled gas cells on the Z-facility as part of the Z Astrophysical Plasma Properties (ZAPP) collaboration. The plasma is diagnosed using a pressure sensor for density and X-ray absorption spectroscopy for charge-state distribution. The electron temperature is presently inferred from a Li-like ion level population ratio, but it is necessary to obtain an independent temperature measurement, as photoionization alters the charge state distribution and can therefore cause errors in temperatures obtained via line ratio techniques. Optical Thomson scattering is a fitting diagnostic because it directly probes the distribution of plasma particle velocities with respect to a central probe frequency. It is a powerful diagnostic which can produce time and space resolved measurements of electron temperature, as well as, electron density, ion temperature, and average ionization. In this paper, we explore a possible design for an optical Thomson scattering system to supplement X-ray spectroscopic measurements. The proposed design will use equipment that is available on Z, though not yet assembled. Both the feasibility and impact of this new diagnostic are assessed by simulating expected spectra for a range of plasma parameters, thereby demonstrating the sensitivity of this diagnostic.

Nutrient fluxes into an isolated coral reef atoll by tidally driven internal bores

AbstractScott Reef is a remote yet biodiverse coral reef atoll, rising from depths > 1000 m on the edge of the continental shelf of northwestern Australia. An intensive 2‐week field study was conducted to assess how physical oceanographic processes influence reef communities in South Scott's deep (~ 50 m) and expansive (~ 300 km2) semi‐enclosed lagoon. The study covered a spring–neap tidal cycle, during which moored instruments measured temperature and velocities at a lagoon entrance and ship‐based vertical profilers measured water quality parameters. Tidally driven internal bores advected cooler and deeper offshore waters (up to 4.5°C, mean 2.4°C) into the lagoon, which were also richer in nutrients and chlorophyll a than lagoon waters. This offshore water originated from approximately 75 m depth. We used the strong observed relationship between in situ measurements of nitrate and temperature to estimate nitrate concentrations from high temporally and spatially resolved temperature measurements at the lagoon entrance, and then estimated the horizontal nitrate fluxes into the lagoon using the velocity measurements. The depth‐integrated, time‐averaged nitrate flux during spring tides (1.46 kg m−1 d−1) was over three times larger than during neap tides (0.46 kg m−1 d−1), despite a passing tropical storm that temporarily deepened the offshore thermocline and reduced the magnitude of the fluxes. Our observations indicate that colder, deeper, and nutrient‐rich water associated with internal tidal bores during spring tide is likely to be the primary mechanism through which allochtonous nutrients are delivered to benthic and pelagic communities within the lagoon of this isolated atoll.

Temperature determination of superheated water vapor by rotational-vibrational Raman spectroscopy.

We present a novel non-invasive laser-based tool for tracer-free spatially resolved temperature measurement in superheated water vapor at atmospheric pressure. The technique exploits the temperature sensitivity of the rotational-vibrational Raman spectrum of the v1 stretching vibration. This Letter demonstrates the Raman sensor, its application to a steam gasification reactor, and four methods to analyze the Raman spectra in order to obtain the temperature: an equal intensity point approach, a pseudo-isosbestic point approach, and two approaches based on the reconstruction of the Raman band by Gaussian/Lorentzian profiles. The evaluated water vapor temperatures inside a reactor for plasma-assisted gasification are compared to data acquired by supercontinuum absorption spectroscopy.

Investigations into Taylor-Quinney coefficient determination for a 7000 series aluminium alloy using a novel small specimen test technique

Thermo-mechanical coupling is a critical component in the thermodynamics of irreversible processes and is related to the dissipation of thermal energy during plastic straining. The Taylor-Quinney coefficient may be thought of as a ratio between thermally dissipated energy and plastic work, thereby giving insight into the thermo-mechanical coupling term. The inclusion of this parameter in a meaningful way is complicated by the various dependencies that the Taylor-Quinney coefficient may be subject to (e.g. loading rate and temperature). Determination of these dependencies is usually achieved through extensive experimentation, wherein temperature variations are monitored (with reference to an unloaded control sample) in a test piece during mechanical loading. There are practical limitations in full size testing methods however, not least relating to the location of full sized control and loaded samples in an environment chamber/furnace while simultaneously maintaining (control sample) temperature uniformity and high resolution temperature measurement (in the loaded sample). The present work details a method based on a novel small specimen testing technique that is currently under development at the University of Nottingham. A small ring of 7175-T7351 aluminum alloy (approximately 10mm in diameter and 2mm in thickness) is loaded between two pins at room temperature, with the local specimen temperature field monitored during monotonic deformation using an infra-red thermal camera. Experimental results are compared for different pin loading rates (namely 0.1mm/s, 1mm/s, and 10mm/s), with particular emphasis placed on localised temperature variations in areas of expected high plasticity. Differences of approximately 0.6°C were observed between 0.1mm/s and 1mm/s tests, with higher temperatures recorded in the latter. Higher temperatures were also noted at small specimen locations associated with localised plasticity. Fundamental thermal material properties are reported for the 7175 alloy in order to facilitate future analysis and heat equation solution efforts (working towards Taylor-Quinney coefficient determination).

Design of a custom insertable probe platform for measurements of C-2W inner divertor plasma parameters.

A custom motor controlled probe system has been designed to make spatially resolved measurements of temperature, density, flow, and plasma potential in the C-2W inner divertors. Measurements in the inner divertors, which have a 1.7 m radius and are located on either end of the confinement vessel, are critical in order to gauge exactly how local settings affect the plasma conditions, confinement, and stability in the field-reversed configuration core. The inner Divertor Insertable Probe Platform (iDIPP) system consists of a custom motor controlled linear rack and pinion transporter that has a 1.9 m travel length in order to reach the center of the divertor. Mounted to the end of the transporter is a 1 m long segmented probe shaft made of individually floating stainless steel rings to prevent shorting out the electrode plates, which are biased up to 5 kV/m. A variety of interchangeable probe tips, including a triple Langmuir probe, a baffled probe, and a Gundestrup probe, can plug into the end of the probe shaft. Custom UHV coiled cabling comprised of 9 shielded conductors expands/retracts with the motion of the transporter in/out of the divertor. The physics motivating plasma parameter measurements in the inner divertors and the details of the design of the iDIPP system will be discussed.

Spatially resolved temperature measurement in the carbon dioxide arc under different gas pressures.

Carbon dioxide (CO2) is a promising alternative to sulfur hexafluoride for high-voltage circuit breaker applications. It is important to have a detailed understanding of CO2 arc properties. In this paper, radial temperature distribution of the free burning direct current arc in pure CO2 was investigated. Optical emission spectrometry was applied under different pressures (0.5atm, 1atm, and 1.5atm) and at different axial positions (1mm, 2mm, 3mm above the cathode). Assuming local thermodynamic equilibrium, the Fowler-Milne method was adopted for O I 715.67nm and O I 777.19nm in the periphery of the arc, and the single-line method was adopted for C II 657.81nm near the center of the arc. Radial temperature profiles obtained by these two methods were combined at the position where normal temperature was assigned. The results indicate that near the center of the arc, higher pressure would lead to lower temperature; as the distance from the cathode to the position measured increases, the maximum temperature in the arc center would decrease. In addition, the temperature would decrease more sharply toward the periphery if the central temperature of the arc is higher.

Helium line ratio spectroscopy for high spatiotemporal resolution plasma edge profile measurements at ASDEX Upgrade (invited).

The thermal helium beam edge diagnostic has recently been upgraded at the ASDEX Upgrade (AUG) tokamak experiment. Line ratio spectroscopy on neutral helium is a valuable tool for simultaneous determination of the electron temperature and density of plasmas. The diagnostic now offers a temporal resolution of 900 kHz with a spatial resolution of up to 3 mm at 32 lines of sight (LOS) simultaneously. The LOS covers a radial region of 8.5 cm, starting at the limiter radius and reaching into the confined region beyond the separatrix. Two components are of particular importance for the aforementioned hardware improvements. The first is the optical head, which collects the light from the experiment. Equipped with an innovative clamping system for optical fiber ends, an arbitrary distribution pattern of LOS can be achieved to gain radial and poloidal profiles. The second major development is a new polychromator system that measures the intensity of the 587 nm, 667 nm, 706 nm, and 728 nm helium lines simultaneously for 32 channels with filter-photomultiplier tube arrays. Thus, the thermal helium beam diagnostic supplements the AUG edge diagnostics, offering fast and spatially highly resolved electron temperature and density profile measurements that cover the plasma edge and scrape-off layer region. Plasma fluctuations, edge localized modes, filaments, and other turbulent structures are resolved, allowing analysis of their frequency and localization or their propagation velocity.

Optical fiber sensing technology based on Mach-Zehnder interferometer and orbital angular momentum beam

An optical fiber sensing and signal demodulation technology based on Mach-Zehnder interferometer (MZI) and orbital angular momentum (OAM) beam was proposed in this work. One path of the MZI containing only single mode fiber (SMF) emits Gaussian beam, and the other path which contains a segment of two-mode fiber (TMF) generates OAM beam. The OAM beam was generated by offset splicing a segment of TMF with SMF, and then rotating the TMF by using a customized fiber rotator. The interference between the Gaussian beam and the OAM beam generates spiral interference pattern, which can rotate with the change of phase difference between these two beams. A segment of SMF in the Gaussian beam path was used as a sensing fiber, which was placed on a thermostat. When the temperature changes, the phase difference between the Gaussian beam and the OAM beam was changed owing to the thermo-optic effect and thermal expansion effect of the sensing fiber, resulting in the rotation of spiral interference pattern. An optical phase difference demodulation method based on spiral interference pattern feature extraction technology was proposed to demodulate optical phase difference between these two beams. Experimental result shows that the sensing system has a linear temperature measurement sensitivity of 12.67 rad/°C. The temperature measurement resolution is 0.0000122 °C in theory and about 0.005 °C achieved in experiment.

Retrieval of wind, temperature, water vapor and other trace constituents in the Martian Atmosphere

Atmospheric limb sounding is a well-established technique for measuring atmospheric temperature, composition, and wind. The theoretical capabilities of a submillimeter limb sounder placed in low Mars orbit are quantified, with a particular focus on the ability to make profile measurements of line-of-sight wind, temperature, water vapor, deuterated water vapor, several isotopes of carbon monoxide, oxygen-18 carbon dioxide, ozone, and hydrogen peroxide. We identify cases where all such measurements can be made within a single 25–70 GHz wide region of the submillimeter spectrum, enabling use of a single state-of-the-art submillimeter receiver. Six potential spectral regions, approximately centered at 335 GHz, 450 GHz, 550 GHz, 900 GHz, 1000 GHz, and 1130 GHz are found, any one of which can provide a complete measurement suite. The expected precision and vertical resolution of temperature, composition, and wind measurements from instruments in each range are quantified. This work thus follows on from that of Urban et al. (2005), Kasai et al. (2012), and earlier studies, expanding them to consider many alternative observing frequency regions. In general, performance (in terms of measurement precision and vertical resolution) is improved with increasing observation frequency. In part this is due to our choice to assume the same antenna size for each frequency, thus providing a narrower field of view for the higher frequency configurations. The general increase in emission line strengths with increasing frequency also contributes to this improved performance in some cases. However, increased instrument power needs for the higher frequency configurations may argue against their choice in some mission scenarios.

Effects of auxiliary atmospheric state parameters on the aerosol optical properties retrieval errors of high-spectral-resolution lidar.

A detailed assessment is carried out in relation to the influence of the uncertainties associated with the input auxiliary atmospheric state parameters on retrieving aerosol optical properties from high-spectral-resolution lidar (HSRL) observations. The study starts from a review of the main spectral structure of the Rayleigh backscattering followed by evaluating the temperature effects on a backscattering cross section of atmospheric molecules based on numerical simulation. It shows that the transmittance of the background interference filter should be taken into account, depending on the full width at half maximum, although overall temperature dependence is negligible. Based on the Taylor expansion of the Tenti S6 model, the systematic errors arising from input temperature and pressure profiles are analyzed. It is demonstrated that the atmospheric pressure profiles have limited effects on the inversion results of aerosol optical parameters, as the atmospheric pressure is usually quite stable. The relative errors of the aerosol backscatter coefficient mainly stem from temperature profile errors and highly depend on the aerosol concentration. Quantitatively, the aerosol backscatter coefficient error could be larger than 5% with a 3 K deviation of temperature when the backscatter ratio is larger than 1.1. The accuracy of aerosol extinction coefficient retrieval is affected not only by the error in temperature, but also by the error in temperature lapse rate; the retrieval accuracy is more sensitive to the latter than the former. Further analysis based on the sounding temperature data shows that the variation of the temperature inversion layer during the night could induce a bias larger than 0.04 km-1 on the aerosol extinction coefficient retrieval. Therefore, the time resolution of temperature measurement from sounding balloons twice per day is too low to obtain an accurate retrieval of the aerosol optical properties from the HSRL.

An experimental investigation on the unsteady heat transfer process over an ice accreting airfoil surface

In the present study, an experimental investigation was performed in an Icing Research Tunnel available at Iowa State University (i.e., ISU-IRT) to quantify the unsteady heat transfer and dynamic ice accretion process over an airfoil/wing surface under different icing conditions (i.e., dry rime ice accretion vs. wet glaze ice accretion). A theoretic model was developed at first to evaluate the unsteady heat transfer process over the ice accreting airfoil/wing surface in the term of convective heat transfer coefficient. During the experiments, a high-speed infrared (IR) thermal imaging system was used to achieve temporally-resolved measurements of the surface temperature distribution over the ice accreting airfoil/wing surface. The transient behaviors of droplets impingement, surface water runback and dynamic phase changing processes over the airfoil/wing surface were characterized quantitatively based on the quantitative surface temperature measurements. Based on the time evolution of the measured surface temperature distributions over the airfoil/wing surface for the rime ice accretion case, the water collection efficiency distribution around the airfoil surface was determined quantitatively, which was then imported into the theoretic heat transfer model to estimate the convective heat transfer coefficients over the ice accreting airfoil/wing surface. The convective heat transfer coefficient was found to reach its maximum value at the airfoil stagnation point, and decrease gradually at the downstream locations. The formation of the ice roughness near the airfoil leading edge was found to be able to enhance the convective heat transfer process over the airfoil surface, which would further promote the ice formation and accretion over the roughed airfoil surface.

Spatially Resolved Temperature Measurements Above a Burning Wood Pellet Using Diode Laser-Based Two-Line Atomic Fluorescence.

Diode laser-based two-line atomic fluorescence (TLAF) thermometry applied to flames of combusting wood pellets is demonstrated. The temperature above burning wood pellets placed in the hot product gas of gallium seeded laminar flames is measured. The calibration-free technique provides spatially resolved temperatures in one dimension with sufficient temporal resolution to resolve all combustion stages of a pellet, even in highly sooting flames. The temperature above a burning pellet was found to decrease due to the release of volatile gases and the accuracy and precision of the technique is assessed at flame temperatures.

Catalytic partial oxidation of n-octane and iso-octane: Experimental and modeling results

The Catalytic Partial Oxidation (CPO) of two octane isomers, 2,2,4-trimethyl pentane (iso-octane) and n-octane, chosen as representative of gasoline is investigated by means of adiabatic tests and mathematical modeling. CPO experiments were carried out in a lab scale auto-thermal reformer with honeycomb monolith catalysts (2% Rh/α-Al2O3), equipped with probes for spatially resolved measurements of temperature and concentration. Tests were performed with about 50% N2 dilution to prevent risks of deactivation due to catalyst over temperature. The CPO of the two isomers follows similar reaction pathways, which mainly consist of the exothermic combustion reaction and the endothermic steam reforming. This results in a close similarity of the concentration profiles of the main species and of the temperature profiles obtained with the two isomers. On the other hand, gas phase reactions proceed to a different extent and bring about a different distribution of thermal cracking products, iso-octane being more reactive and selective to iso-butylene and propene, while n-octane being selective to ethylene. Coke formation was observed upon adiabatic tests which was responsible for partial deactivation of the reforming zone of the catalyst. Post mortem TPO tests show that n-octane exhibits a higher tendency to coke deposition than iso-octane in the adopted CPO conditions. Thermodynamic and modeling calculations show that the risk of coking can be reduced by using exhaust gas recycling instead of N2 to dilute the reactants.

Acoustic detection of resonance-enhanced multiphoton ionization for spatially resolved temperature measurement

In this Letter, acoustic detection of resonance-enhanced multiphoton ionization (A-REMPI) is characterized and used to measure spatially resolved O2 rotational temperature in air. The acoustic signal is generated using O2 REMPI in air and is detected by a single microphone operating within the audible range. Compared to electron number measurements by coherent microwave scattering, nonlinear light absorption and subsequent local pressure perturbation are captured by the microphone. A typical acoustic cycle of compression and rarefication of the acoustic wave is observed in the A-REMPI. Since the pressure perturbation can be regarded as close to thermodynamic equilibrium, the rotational temperature measured by A-REMPI is lower and closer to the realistic condition.