Characteristics of the SOL ion-to-electron temperature ratio on the J-TEXT tokamak with different plasma configurations

Accurate measurement of the average plasma parameters in the edge region,including the temperature and density of electrons and ions,is critical for understanding the characteristics of the scrape-off layer(SOL) and divertor plasma transport in magnetically confined fusion research.On the J-TEXT tokamak,a multi-channel retarding field analyzer(RFA) probe has been developed to study average plasma parameters in the edge region under various poloidal divertor and island divertor configurations.The edge radial profile of the ion-to-electron temperature ratio,τ_(i/e),has been determined,which gradually decreases as the SOL ion self-collisionality,v_(SOL)*,increases.This is broadly consistent with what has been observed previously from various tokamak experiments.However,the comparison of experimental results under different configurations shows that in the poloidal divertor configuration,even under the same v_(SOL)*,τ_(i/e) in the SOL region becomes smaller as the distance from the X-point to the target plate increases.In the island divertor configuration,τ_(i/e) near the O-point is higher than that near the X-point at the same v_(SOL)*,and both are higher than those in the limiter configuration.These results suggest that the magnetic configuration plays a critical role in the energy distributions between electrons and ions at the plasma boundary.

Frequency dependence of electron temperature in hollow cathode-type discharge as measured by several different floating probe methods

We measured electron temperatures through a hollow cathode-type discharge tube using several different floating probe methods. This method detected a shift in the floating potential when an AC voltage was applied to a probe through an intermediary blocking capacitor. The shift in the floating potential is described as a function of the electron temperature and the applied AC voltage. In this study, the effects of the frequency and waveform on the electron temperatures were systematically investigated. The electron temperature measured when using the floating probe method with applied sinusoidal and triangular voltages was lower than that measured with an applied rectangular voltage.The value in the high frequency range was close to that of the tail electron temperature.

Electron Temperature Measurement by Floating Probe Method Using AC Voltage

This study presents a novel floating probe method to measure electron temperatures using a hollow cathode-type discharge tube. The proposed method detects a shift in the floating potential when an AC voltage is applied to a probe through an intermediary blocking capacitor. The shift in the floating potential is described as a function of the electron temperature and the applied AC voltage. The floating probe method is simpler than the Langmuir probe method because it does not require the measurement of volt-ampere characteristics. As the input AC voltage increases, the electron temperature converges. The electron temperature measured using the floating probe method with an applied sinusoidal voltage shows a value close to the first （tail） electron temperature in the range of the floating potential.

High-precision nuclear magnetic resonance probe suitable for in situ studies of high-temperature metallic melts

High-temperature nuclear magnetic resonance(NMR)has proven to be very useful for detecting the temperatureinduced structural evolution and dynamics in melts.However,the sensitivity and precision of high-temperature NMR probes are limited.Here we report a sensitive and stable high-temperature NMR probe based on laser-heating,suitable for in situ studies of metallic melts,which can work stably at the temperature of up to 2000 K.In our design,a well-designed optical path and the use of a water-cooled copper radio-frequency(RF)coil significantly optimize the signal-to-noise ratio(S/NR)at high temperatures.Additionally,a precise temperature controlling system with an error of less than±1 K has been designed.After temperature calibration,the temperature measurement error is controlled within±2 K.As a performance testing,^(27)Al NMR spectra are measured in Zr-based metallic glass-forming liquid in situ.Results show that the S/NR reaches 45 within 90 s even when the sample's temperature is up to 1500 K and that the isothermal signal drift is better than0.001 ppm per hour.This high-temperature NMR probe can be used to clarify some highly debated issues about metallic liquids,such as glass transition and liquid-liquid transition.

New Measuring Temperature Setup with Optical Probe

Abstract: A new setup of measuring temperature is developed, which the probe is a micro- power consumptive one with CMOS circuit and is driven by optical power. For transmitting the measured signal and optical power signal in a long distance, the fiber technology is applied in this setup.

Influence of Temperature Probes Installation on the Salient Pole to Temperature Measurement

Accurate and reliable information about the temperature of the synchronous generators excitation winding hot spot is necessary to determine the dynamic limit caused by excitation winding overheating in the PQ diagram. For good estimation of a position and the hot spot temperature it is decided to mount 19 temperature probes on one pole of the 6-pole, 400 kVA. 50 llz synchronous generator. Due to a large number of the probes and because the probes should be glued with the metal epoxy it was assumed that mounting of the probes will disrupt the temperature field of the excitation winding. To get the answer to this question the excitation winding resistance was measured betbre and after mounting the probes, in a hot and a cold state. Temperature rise can be estimated if the resistance ratio in the hot and the cold state is known. The paper also addresses the analysis of the measurement accuracy. The result shows that, there is no significant influence on the temperature when mounting the 19 temperature probes which covered 10% of the pole excitation winding surface.

Effect of Temperature on Gas Hold-up in Aerated Stirred Tanks

Gas holdups in ambient gassed and hot sparged systems with multiple modern impellers and the effect of temperature on gas holdup are reported. The operating temperature has a great impact on gas holdup though the gas dispersion regime in the hot sparged system is similar to the ambient gassed condition. The gas holdup under the elevated temperature and the ambient gassed operation is successfully correlated. With the same total gas flow rate and power input, the gas holdup in the hot sparged system (say near the boiling point) is only about half of that in the ambient system. The results imply that almost all existing hot sparged reactors have been designed on the basis of incorrect estimates of the gas holdup during operation.

GROUND TEMPERATURE AND ROCK THERMOPHYSICAL PROPERTIES IN FILDES PENINSULA

During 1985-1986, 1986-1987, and 1988-1989 expeditions on Fildes Peninsula the ground temperature was measured. A total number of 218 ground temperature data were obtained. The thermal conductivity measurements were made on 121 rock samples collected during expedition. This article gives a brief analysis and summarization of these data.

Temperature measurement based on radialization power for micro-hotplate

A novel method to measure the temperature on the surface of micro-hotplate was presented. The tiny fiber probe and the optical power meter were employed to measure the sample radialization power. By means of comparing the relationship between the radialization power and the temperature, sample surface temperature can be discerned accurately. Such an approach has provided more accuracy than traditional temperature measurements. The experimental result based on this method is quite similar to that of simulation by the finite element analysis (FEA) software of Ansys in theory. This measurement is very useful for measuring temperature for these micro samples prone to be untouchable.

Symmetric Temperature Compensation for Photoelectric Coupling Current Transducer

The temperature characteristic of sensor probe at high voltage side is analyzed by using a photoelectric coupling current transducer. The principle of symmetric temperature compensation and the main idea of software design are proposed. The method increases measuring precision and has fairly great practicability.

Plasma potential measurements using an emissive probe made of oxide cathode

A novel emissive probe consisting of an oxide cathode coating is developed to achieve a low operating temperature and long service life.The properties of the novel emissive probe are investigated in detail,in comparison with a traditional tungsten emissive probe,including the operating temperature,the electron emission capability and the plasma potential measurement.Studies of the operating temperature and electron emission capability show that the tungsten emissive probe usually works at a temperature of 1800 K-2200 K while the oxide cathode emissive probe can function at about 1200 K-1400 K.In addition,plasma potential measurements using the oxide cathode emissive probe with different techniques have been accomplished in microwave electron cyclotron resonance plasmas with different discharge powers.It is found that a reliable plasma potential can be obtained using the improved inflection point method and the hot probe with zero emission limit method,while the floating point method is invalid for the oxide cathode emissive probe.

Study of plasma parameters of coaxial plasma source using triple Langmuir probe and Faraday cup diagnostics

Coaxial plasma guns are a type of plasma source that produces plasma which propagates radially and axially controlled by the shape of the ground electrode, which has attracted much interest in several applications. In this work, a 120° opening angle of CPG nozzle is used as a plasma gun configuration that operates at the energy of 150 J. The ionization of polyethylene insulator between the electrodes of the gun produces a cloud of hydrogen and carbon plasma.The triple Langmuir probe and Faraday cup are used to measure plasma density and plasma temperature. These methods are used to measure the on-axis and off-axis plasma divergence of the coaxial plasma gun. The peak values of ion densities measured at a distance of 25 mm on-axis from the plasma gun are(1.6±0.5)×10^(19)m^(-3)and(2.8±0.6)×10^(19)m^(-3)for hydrogen and carbon plasma respectively and the peak temperature is 3.02±0.5 eV. The mean propagation velocity of plasma is calculated using the transit times of plasma at different distances from the plasma gun and is found to be 4.54±0.25 cm/μs and 1.81±0.18 cm/μs for hydrogen and carbon plasma respectively. The Debye radius is obtained from the measured experimental data that satisfies the thin sheath approximation. The shot-to-shot stability of plasma parameters facilitates the use of plasma guns in laboratory experiments. These types of plasma sources can be used in many applications like plasma opening switches, plasma devices, and as plasma sources.

The Langmuir Probe onboard CSES: data inversion analysis method and first results

The Langmuir Probe(LAP), onboard the China Seismo-Electromagnetic Satellite(CSES), has been designed for in situ measurements of bulk parameters of the ionosphere plasma, the first Chinese application of in-situ measurement technology in the field of space exploration. The two main parameters measured by LAP are electron density and temperature. In this paper, a brief description of the LAP and its work mode are provided. Based on characteristics of the LAP, and assuming an ideal plasma environment, we introduce in detail a method used to invert the I-V curve; the data products that can be accessed by users are shown. Based on the LAP data available, this paper reports that events such as earthquakes and magnetic storms are preceded and followed by obvious abnormal changes. We suggest that LAP could provide a valuable data set for studies of space weather, seismic events, and the ionospheric environment.

Sweep Langmuir Probe and Triple Probe Diagnostics for Transient Plasma Produced by Hypervelocity Impact

Two techniques are applied to diagnose characteristic parameters of plasma created by hypervelocity impact, such as electron temperature and electron density. The first technique is a sweep Langmuir probe （SLP）, which is a new apparatus based on a dual channel circuit that can compensate for stray capacitance and obtain a good synchronicity, so that electrostatic turbulence with a good temporal resolution can be acquired. The second technique is a triple Langmuir probe （TLP）, which is an electrostatic triple Langmuir probe diagnostic system, in which no voltage and frequency sweep is required. This technique allows to measure electron temperature, electron density as a function of time. Moreover, the triple Langmuir probe diagnostic system allows the direct display of electron temperature and semidirect display of electron density by an appropriate display system, the system permits us to eliminate almost all data processing procedures. SLP and TLP were applied to obtain fluctuations of the characteristic parameters of plasma generated by hypervelocity impact. As an example of their application to time-dependent plasma measure- ment, the electron temperature and electron density of plasmas were acquired in hypervelocity impact experiments. Characteristic parameters of plasma generated by hypervelocity impact were compared by the two kinds of diagnostic techniques mentioned above.

Application of Electrostatic Probe in Wool Fabric LTP Finishing

By using a double electron probe the electron density and electron temperature were measured during the low temperature plasma （LTP） treatment of wool fabrics. The dependences of the electron density upon the power, pressure and the plasma-treating time was studied. The effects on the wool fabrics＇ shrinkage were studied. The results showed that the angle of the double electrostatic probe and the area of the treated fabrics had a strong impact on the density measurement. The felt-proof property of wool fabrics treated with an argon plasma was better than that with a nitrogen plasma. The gas, power and pressure of the LTP treatment all affected the electron density. The electron density increased with the increase in power and pressure. The electron density did not change significantly with treating time, in a certain range of both power and pressure of the LTP treatment.

Optimization of Langmuir Probe System Parameters in a Stationary Laboratory Plasma

In order to obtain creditable data an applicable method to optimize parameters of the Langmuir probes and circuits in a stationary laboratory device is investigated and an experimental criterion of the probe dimension is developed. To obtain the electron temperature and density the Electron Energy Distribution Function （EEDF） approach with less computing time and more accurate results is applied, instead of the conventional slope approach. Moreover the influence of the vessel wall materials on the plasma density is discussed briefly, indicating that the dielectric wall is helpful to enhancing the electron density.

Influence of Working Pressure on Ion Sensitive Probe Measurement in Microwave ECR Plasmas

In order to precisely measure the ion parameters in a microwave electron cyclotron resonance plasma using an ion sensitive probe,the dependences of the current-voltage（I-V）characteristics on the shielding height（h）and the potential difference between inner and outer electrodes（V_B）have been investigated at different working pressures of 0.03 Pa and 0.8 Pa.Results show that the I-V curves at higher pressure are more sensitive to the variation of h than those at lower pressure.The influence of V_B on ion temperature（T_i）measurement becomes more prominent when the pressure is increased from 0.03 Pa to 0.8 Pa.Under both pressures,the optimized h is obtained at the condition where the current reaches zero in the positive voltage region with a suitable V_B of-1.5 V because of effective shielding of the electron E×B drift.

Measurement of Plasma Density in Brass Arc Plasma at Atmospheric Pressure Using a Langmuir Single Probe

In this work, we construct electrodes of brass to produce plasma by arc discharge and is characterized by using a movableLangmuir single probe. It is a simple way to measure plasma parameters such as electron temperature, electron density and iondensity. A movable Langmuir single probe technique has a reference point since it is biased with reference to any one electrode ofthe plasma producing system. The values obtained are at atmospheric pressure. The plasma thus produced in laboratory has variousapplications which include gaseous discharge, plasma torch, sputtering, laser produced plasma as well as tokamak plasma.

BRCA1 Mutation Detection Using Fluorescent Hybridization Probes and Melting Curves

The BRCA1 （Breast Cancer Anti-estrogen resistance-I）, early-onset gene is expressed in cells of breast and other tissue and helps to repair damaged DNA or destroy cells in cases DNA cannot be repaired. When the BRCA1 gene is damaged, then the DNA is not repaired appropriately and this enhances the risk for cancer. Fluorescence and UV-visible thermal studies were performed for WT （wild type） and MT （mutant type targets） full systems. The target DNAs used were in the form of short oligonucleotides, genomic DNA. The probe system was used for detection of WT and SNP alleles of human BRCAI [（170-190, G---~T） and （290-310, G---~T）]. The Cy5 dye attached to a probe oligonucleotide （10-mer） undergoes a fluorescence intensity change on hybridisation of the probe to the WT compared to MT targets. Our results indicate that the system consisting of the target sequence and the one probe oligonucleotides bearing the Cy5 dye assemble correctly at the specified target. Once the full system （probe and target） is arranged under suitable conditions, a red-shift emission and change in fluorescence intensity are seen at a suitable wavelength. Thermal studies also showed significant differences in T,, between WT and MT. The results suggest that the differences in the fluorescence intensity at 665 nm and the spectrophotometric T,,,cs） for the WT and MT can be attributed to the type of binding of the probe to the target. The systems were sensitive to single nucleotide polymorphisms and this may help in high throughput applications in genetic testing and molecular diagnostics.

基于总温探针的高精度总焓测量方法优化研究

为提高中低焓来流的总焓测量精准度,以铱铑铱热电偶为测温元件研制了一种总温探针。基于流热耦合计算模型对该探针各部件尺寸参数进行了优化设计,使得总温探针的复温率不低于0.9;计算和试验结果表明铱铑铱热电偶结点温度会随着热电偶后端面温度和屏蔽罩温度的升高而缓慢升高,导致不同测量时间段下得到的总温值不同,因此必须规定测量时间段并进行溯源校准。为此,借助一种新设计的加热器弧室总温探针,将应用于电弧风洞超声速流场的总温探针向亚声速流场总温校准装置进行了溯源校准。在电弧风洞中开展了总焓测量验证试验,采用基于精度极限和偏差极限的不确定度评估方法,计算了总焓测量结果的不确定度。结果表明:所研制的总温探针具有较高的总焓测量精准度,就本文试验结果而言,其重复性精度约为3%,不确定度约为6.4%。