Increasing Heating Power Research Articles

Integrated modelling of H-mode pedestal and confinement in JET-ILW

A pedestal prediction model Europed is built on the existing EPED1 model by coupling it with core transport simulation using a Bohm-gyroBohm transport model to self-consistently predict JET-ILW power scan for hybrid plasmas that display weaker power degradation than the IPB98(y, 2) scaling of the energy confinement time. The weak power degradation is reproduced in the coupled core-pedestal simulation. The coupled core-pedestal model is further tested for a 3.0 MA plasma with the highest stored energy achieved in JET-ILW so far, giving a prediction of the stored plasma energy within the error margins of the measured experimental value. A pedestal density prediction model based on the neutral penetration is tested on a JET-ILW database giving a prediction with an average error of 17% from the experimental data when a parameter taking into account the fuelling rate is added into the model. However the model fails to reproduce the power dependence of the pedestal density implying missing transport physics in the model. The future JET-ILW deuterium campaign with increased heating power is predicted to reach plasma energy of 11 MJ, which would correspond to 11–13 MW of fusion power in equivalent deuterium–tritium plasma but with isotope effects on pedestal stability and core transport ignored.

Global Alfvén eigenmodes in the H-1 heliac

Recent upgrades in H-1 power supplies have enabled the operation of the H-1 experiment at higher heating powers than previously attainable. A heating power scan in mixed hydrogen/helium plasmas reveals a change in mode activity with increasing heating power. At low power ( kW) modes with beta-induced Alfvén eigenmode frequency scaling are observed. At higher power modes consistent with an analysis of nonconventional global Alfvén eigenmodes (GAEs) are observed, the subject of this work. We have computed the mode continuum, and identified GAE structures using the ideal MHD solver CKA and the gyrokinetic code EUTERPE. An analytic model for ICRH-heated minority ions is used to estimate the fast ion temperature from the hydrogen species. Linear growth rate scans using a local flux surface stability calculation, LGRO, are performed. These studies demonstrate drive from the radial spatial gradient of circulating particles whose speed is significantly less than the Alfvén speed, and are resonant with the mode through harmonics of the Fourier decomposition of the strongly shaped heliac magnetic field. They reveal drive is possible with a small hot energetic tail of the hydrogen species, for which . Local linear growth rate scans are also complemented with global calculations from CKA and EUTERPE. These qualitatively confirm the findings from the LGRO study, and show that the inclusion of finite Larmor radius effects can reduce the growth rate by a factor of up to ten, and increases the marginal stability fast ion temperature by a factor of two. Finally, a study of damping of the global mode with the thermal plasma is conducted, computing continuum damping , and the damping arising from finite Larmor radius and parallel electric fields (via resistivity). We find that continuum damping is of order 0.1% for the configuration studied. A similar calculation in the cylindrical plasma model produces a frequency 35% higher and a damping 30% of the three-dimensional result: this confirms the importance of strong magnetic shaping to the frequency and damping. The inclusion of resistivity lifts the damping to . Such large damping is consistent with experimental observations that in absence of drive the mode decays rapidly (∼0.1 ms).

Experimental investigation of two-phase closed thermosyphon used in heavy duty extrusion pelleting line

Efficient cooling system is an essential part of heavy duty extrusion pelleting line which plays an important role in production engineering of megaton polyolefin. In this paper, a new cooling system based on two-phase closed thermosyphon (TPCT) used in heavy duty extrusion pelleting line was presented. Comparative experimental results show that thermal performance of TPCT is more efficient, and the temperature uniformity is much better than traditional extruder (similar to coiled heat exchanger) in preheating process and extrusion reaction process. The effects of different operation conditions: filling ratio (0.2, 0.35, 0.5, 0.65 and 0.8), flow rate of cooling water (120L/h, 180L/h, 240L/h, 300L/h and 360L/h) and heating power (7kW, 9kW and 11kW) on thermal characteristics were experimental investigated, respectively. The results show that temperature of barrel inner wall increased significantly as filling ratio increased and evaporator appeared dry out when filling ratio is 0.2. The flow rate of cooling water affected the condenser section obviously, but had little influence on evaporation section. With increase of heating power, the start-up time decreases and the heat transfer coefficient increased. An ideal cooling scheme was concluded: the liquid filling ratio was 0.35, the cooling water flow rate was 180L/h and the heating power was 11kW when working medium was water.

Numerical and experimental study of electron beam floating zone melting of Iridium single crystal

Both numerical and experimental approaches were conducted to investigate the electron beam floating zone melting (EBFZM) of iridium crystal. A finite element model was established and the temperature fields under different processing parameters were calculated and discussed. The heating power, the rod diameter and the movement of heating source significantly influence the temperature distribution in the iridium rod. Once the heating starts, the temperature quickly increases and gradually reaches the steady state. The melting zone enlarges with the increase of heating power, and the critical power for obtaining a complete melting zone is 5.5kW∼6.0kW in 20mm-diameter Iridium rod. With the upward movement of heating source, the melting zone obviously enlarges and the lower solid/liquid (S/L) interface becomes more planar. Then how to get a complete melting zone with a suitable volume and the control of a planar S/L interface were discussed. An optimized processing window was proposed and applied to the EBFZM of iridium crystal. An iridium rod 20mm in diameter was successfully produced and the microstructural morphologies indicated that the initial polycrystalline microstructure will evolve into single crystal.

Modelling of transitions between L- and H-mode in JET high plasma current plasmas and application to ITER scenarios including tungsten behaviour

The dynamics for the transition from L-mode to a stationary high Q DT H-mode regime in ITER is expected to be qualitatively different to present experiments. Differences may be caused by a low fuelling efficiency of recycling neutrals, that influence the post transition plasma density evolution on the one hand. On the other hand, the effect of the plasma density evolution itself both on the alpha heating power and the edge power flow required to sustain the H-mode confinement itself needs to be considered. This paper presents results of modelling studies of the transition to stationary high Q DT H-mode regime in ITER with the JINTRAC suite of codes, which include optimisation of the plasma density evolution to ensure a robust achievement of high Q DT regimes in ITER on the one hand and the avoidance of tungsten accumulation in this transient phase on the other hand.As a first step, the JINTRAC integrated models have been validated in fully predictive simulations (excluding core momentum transport which is prescribed) against core, pedestal and divertor plasma measurements in JET C-wall experiments for the transition from L-mode to stationary H-mode in partially ITER relevant conditions (highest achievable current and power, H 98,y ~ 1.0, low collisionality, comparable evolution in P net/P L-H, but different ρ *, T i/T e, Mach number and plasma composition compared to ITER expectations). The selection of transport models (core: NCLASS + Bohm/gyroBohm in L-mode/GLF23 in H-mode) was determined by a trade-off between model complexity and efficiency. Good agreement between code predictions and measured plasma parameters is obtained if anomalous heat and particle transport in the edge transport barrier are assumed to be reduced at different rates with increasing edge power flow normalised to the H-mode threshold; in particular the increase in edge plasma density is dominated by this edge transport reduction as the calculated neutral influx across the separatrix remains unchanged (or even slightly decreases) following the H-mode transition.JINTRAC modelling of H-mode transitions for the ITER 15 MA / 5.3 T high Q DT scenarios with the same modelling assumptions as those being derived from JET experiments has been carried out. The modelling finds that it is possible to access high Q DT conditions robustly for additional heating power levels of P AUX ⩾ 53 MW by optimising core and edge plasma fuelling in the transition from L-mode to high Q DT H-mode. An initial period of low plasma density, in which the plasma accesses the H-mode regime and the alpha heating power increases, needs to be considered after the start of the additional heating, which is then followed by a slow density ramp. Both the duration of the low density phase and the density ramp-rate depend on boundary and operational conditions and can be optimised to minimise the resistive flux consumption in this transition phase. The modelling also shows that fuelling schemes optimised for a robust access to high Q DT H-mode in ITER are also optimum for the prevention of the contamination of the core plasma by tungsten during this phase.

Experimental investigation of heat transfer and pressure drop in a straight minichannel heat sink using TiO2 nanofluid

In this paper, heat transfer and pressure drop characteristic associated with minichannel heat sink is investigated experimentally. TiO2 nanofluid with 15% weight concentration in water as base fluid is used as a coolant and its performance is compared with the distilled water at heating powers of 100W, 125W and 150W. The results indicate that TiO2 nanofluid thermal performance is strongly dependent on heating power and its usefulness heat transfer characteristic could be achieved more effectively at lower heating power. However, pressure drop is found to increase with the decrease of heating power and this decrement is more prominent for TiO2 nanofluid as compared to distilled water due to viscosity variation with temperature. Nusselt number is found invariant with increase or decrease of heating power and hence using distilled water, experimental Nusselt number satisfies Peng and Peterson empirical correlation at all heating powers within 20% accuracy. The lowest wall temperature is measured to be 37.05°C using TiO2 nanofluid at Reynolds number of 922 corresponding to heating power of 100W. Moreover, while passing through the minichannel, an axial rise of base temperature is observed from inlet to outlet of heat sink.

Minimum age for clear-cutting native species with energetic potential in the Brazilian semi-arid region

What is the minimum age for clear-cutting native species with energetic potential in the Brazilian semi-arid region? This was the central question of this study, which aimed at estimating the minimum cutting cycle for native woody species from an area covered by a sustainable forest management plan. Individuals (n = 240) of 12 species native to the semi-arid region were measured, and wood discs were taken from them to collect data relative to (i) volume, by an industrial 3D scanner, (ii) density, using a high-frequency densitometer, (iii) age, by a growth ring measuring device, and (iv) the lower heating value, by an oxygen bomb calorimeter and an elemental analyzer. Data were fitted to mathematical models by regression analysis to determine the relationship and significance between the variables analyzed. The estimated minimum age for the harvesting of native woody species was 47 years, determined by the age at which there was stabilization of volume growth curves over time and an increase in density and heating power (wood retraction).

Experimental research on the start-up characteristics and heat transfer performance of pulsating heat pipes with rectangular channels

As a simple and efficient heat transfer device, the pulsating heat pipe (PHP) has been considered as one of the most effective methods to meet the challenges of high heat flux. Current studies focused on the heat transfer performance of the PHP with a small diameter (d≤3mm). However, the PHP with a relatively large diameter has better performance due to the larger heat capacity of the working fluid at the same filling ratio. Besides, compared with the PHP with circular channels, the PHP with rectangular channels has special advantages due to the unique structures. On the basis of this, an experimental setup of the PHP with rectangular channels of 4mm equivalent inner diameter was built, and the influence of cross-section shape on the start-up characteristics and heat transfer performance of the PHP was investigated. The experimental results showed that the start-up process shifted from a “sudden start-up mode” to a “smooth start-up mode” with the increase of heating power. The start-up heating power of the PHP with rectangular channels was (1.5–2) times greater as the heating power of the PHP with circular channels. Furthermore, the thermal resistance of the PHP with rectangular channels was only (30–40)% of the PHP with circular channels, and the temperature differences between the evaporation section and the condensation section were (10–20)°C lower than those of the PHP with circular channels under the same filling ratio and heat flux. It could also be concluded from the results that the lowest thermal resistance was achieved when filling ratio was 0.3 within the range of experimental data. The experimental results will provide valuable references for the optimal design of the PHP and further studies.

Nickel-ammonia loop heat pipe based on the molten salt pore forming startup and heat transfer failure characteristics of experimental study

Loop heat pipe was widely used in the field of aerospace and electronic cooling as an efficient phase change heat transfer components. The research developed a kind of stainless steel nickel ammonia loop heat pipe using the method of molten salt pore-forming, experimental study was conducted for the startup characteristic and failure characteristics of heat transfer. Experimental finding: the nickel-ammonia loop heat pipe can start when the heating power was 6w, and start time only needed 3 minutes; with the increase of heating power, heat pipe startup time increased; with the increase of heating power, loop heat pipe showed a good heat transfer characteristics when When the heating power was less than 30w; the higher of the heat load, the greater of the evaporator and steam temperature; when the load exceeded 3w, loop heat pipe evaporator will appear dry phenomenon, lead to heat pipe failure and the greater of power, the faster of the heat pipe will be failure.

Simulation on the Thermal Properties of Polymer Composites Reinforced by Buckypaper

FLUENT was used to analyze how the bending cycles of buckypaper affects the temperature distribution, the changes of the temperature with time and the heating rate during heating. The typical temperature decreases with the increase of bending cycles of the buckypaper. The typical temperature increases with the increase of heating power. The temperature distribution of the polymer composites is more uniform with the increase of bending cycles of buckypaper. The difference of the maximum and minimum temperature of the composites increases linearly with the increase of heating power. The average temperature of the composites when reaching the stable state increase as the bending cycles of buckypaper decrease. The difference of the maximum and minimum temperature of the composites decreases with the increase of the bending cycles.

The melting process of a freezing molten salt pipe of concentracted solar power plant

Concentrated solar power plants are potential to provide based load power of the future electrical power system. Commercial concentrated solar power plants using molten salt as the heat transfer fluid and the energy storage medium have been built and show great promising. However, due to high freezing point, the molten salt has a freezing possibility and may block the pipe. In practical, an electrical heat tracing is installed along the flow path of the molten salt to protect against freezing. Once the molten salt is freezing inside the pipe, the electrical heat tracing can be used to melt the molten salt. This paper studied the melting process of a molten salt (60% NaNO3 and 40% KNO3, referred to as Solar Salt) inside a horizontal pipe by an electrical heat tracing. The molten salt is a binary mixture, its freezing point (511 K) is higher than melting point (494 K). A solid-liquid mixture mushy zone exists between the melting point and the freezing point during the melting process. The enthalpy method was used to simulate the solid-liquid phase change phenomenon of the molten salt. The effect of the natural convection inside the pipe was also considerate. The effect of the installation position and the heating power of the electrical heat tracing on the melting process and the melting time were studied. During the heating process, the molten salt close to the electrical heat tracing melts first and forms a mushy zone. With the assistance of the natural convection, the molten salt in the mushy zone flows upward and gathers in the upper zone of the pipe. Thus, the upper zone of the pipe has a higher liquid fraction than the lower zone, which results in a liquid fraction gradient inside the pipe. The results show than the installation position of the electrical heat tracing effects the gradient of the liquid fraction during the melting process. The increase in the angle between the gravity and the installation position, γ , increases the liquid fraction gradient. It takes a same time to completely melt the molten salt when γ equals to 30° and 60°. When γ is 90°, due to a larger liquid fraction gradient, it needs more 5 min than γ is 60°. Therefore, large γ should be avoided for the practically installation of the electrical heat tracing. The results also show that the melting time is 165 min for a 35 W/m heating power, 85 min for 70 W/m, and 51 min for 140 W/m. Increasing the heating power from 35 W/m to 70 W/m can shorten 48.5% of the melting time, while increasing the heating power from 70 W/m to 140 W/m can only shorten 40% of the melting time. This is because a higher electrical heating power increases the liquid fraction gradient of the mushy zone during the melting process. Thus, the percentages of the shorten melting time decreases with the increases of the heating power. This study gives practical reference to the choose and the installation of the electrical heating tracing of the molten salt pipe.

Impact of lithium pellets on plasma performance in the ASDEX Upgrade all-metal-wall tokamak

The impact of lithium (Li) on plasma performance was investigated at the ASDEX Upgrade tokamak, which features a full tungsten wall. Li pellets containing 1.6 × 1020 Li atoms were launched with a speed of 600 m s−1 to achieve deep penetration into the plasma and minimize the impact on the first wall. Homogeneous transient Li concentrations in the plasma of up to 15% were established. The Li sustainment time in the plasma decreased with an increasing heating power from 150 to 40 ms. Due to the pellet rate being restricted to 2 Hz, no Li pile-up could take place. No significant positive impact on plasma properties, as reported from other tokamak devices, could be found; the Li pellets rather caused a small reduction in plasma energy, mainly due to enhanced radiation. Due to pellet injection, a short-lived Li layer was formed on the plasma-facing components, which lasted a few discharges and led to moderately beneficial effects during plasma start-up. Most pellets were found to trigger type-I ELMs, either by their direct local perturbation or indirectly by the altered edge conditions; however, reliability was less than 100%.

Role of a MHD mode crash in triggering H-mode at marginal heating power on the HL-2A tokamak

The impact of a low frequency MHD mode crash on triggering the H-mode has been studied in detail on the HL-2A tokamak. The mode manifests fishbone characteristics with a precession frequency f≈14–19 kHz. The abrupt mode crash evokes substantial energy release from the core to the plasma boundary and hence increases the edge pressure gradient and Er×B flow shear, which further suppresses turbulence and leads to confinement improvement into the H-mode. Under the same NBI heating (∼1 MW), the I-phase plasma transits into H-mode with a rapid MHD mode crash while it returns to the L-mode without the presence of the mode in the I-phase. With increasing heating power by the ECRH added to the NBI, the MHD mode disappears. The statistical result shows that with the MHD mode crash the heating power for accessing the H-mode is significantly lower than that without the mode crash. All these facts reveal that the MHD mode crash in the I-phase plays a critical role in trigging the I→H transition at marginal heating power. In addition, it has been found that with the same NBI power heating, the magnitude of the mode (crash) increases with increasing plasma density, implying larger energy release being needed to access the H-mode for higher density plasmas.

Study of improved confinement by a stepwise increase of the input heating power for tokamak plasmas

This paper is an extension of the brief study by Sarah Douglas et al. [Phys. Plasmas 20 (2013) 114504] where in the study a sinusoidal perturbation of the heating power has been studied. In this paper a stepwise increase of the heating power and its influence on the [Formula: see text]–[Formula: see text] transition are studied. Using a function, [Formula: see text] for the transition of input heating power for tokamak plasmas, i.e. the addition of the perturbation, [Formula: see text], to constant power [Formula: see text] is shown to promote the confinement, leading to the [Formula: see text]–[Formula: see text] transition at a lower value of [Formula: see text], as compared to the case of constant [Formula: see text] without the [Formula: see text] perturbation. It is seen that the input heating power [Formula: see text] that consists of constant part [Formula: see text] in addition to a function [Formula: see text] provides the [Formula: see text]–[Formula: see text] transition for relatively small [Formula: see text] and much wider range values of [Formula: see text] as compared to Sarah Douglas et al. [Phys. Plasmas 20 (2013) 114504].

Experiment study of oscillating heat pipe and phase change materials coupled for thermal energy storage and thermal management

In order to enhance the thermal performance of latent heat thermal energy storage (LHTES) system and thermal management system, a novel method that coupling oscillating heat pipe (OHP) and phase change materials (PCM) was proposed and investigated in this paper. The advantages of PCM and OHP could be combined to overcome each shortcoming. The expanded graphite (EG)/paraffin composite material and the closed loop OHP used in the experiment were prepared and tested. The thermal performance of the coupling module was studied experimentally under different operating conditions. The results showed that the angle range where thermal resistance is obviously affected by the installation angle decreases with the increase of heating power. The trend of the temperature difference between the closed loop OHP and EG/paraffin composite before the PCM melting was similar to those filled with water under the same condition, but the difference value was larger. The working condition of the OHP directly affects the thermal efficiency of the coupling system. The oscillation and the temperature variation have good synchronization. Relative to the EG/paraffin composite, it took about two times time for the paraffin to release heat from the same starting temperature to the ambient temperature.

Design, R&D and commissioning of EAST tungsten divertor

After commissioning in 2005, the EAST superconducting tokamak had been operated with its water cooled divertors for eight campaigns up to 2012, employing graphite as plasma facing material. With increase in heating power over 20 MW in recent years, the heat flux going to the divertors rises rapidly over 10 MW m−2 for steady state operation. To accommodate the rapid increasing heat load in EAST, the bolting graphite tile divertor must be upgraded. An ITER-like tungsten (W) divertor has been designed and developed; and firstly used for the upper divertor of EAST. The EAST upper W divertor is modular structure with 80 modules in total. Eighty sets of W/Cu plasma-facing components (PFC) with each set consisting of an outer vertical target (OVT), an inner vertical target (IVT) and a DOME, are attached to 80 stainless steel cassette bodies (CB) by pins. The monoblock W/Cu-PFCs have been developed for the strike points of both OVT and IVT, and the flat type W/Cu-PFCs for the DOME and the baffle parts of both OVT and IVT, employing so-called hot isostatic pressing (HIP) technology for tungsten to CuCrZr heat sink bonding, and electron beam welding for CuCrZr to CuCrZr and CuCrZr to other material bonding.Both monoblock and flat type PFC mockups passed high heat flux (HHF) testing by means of electron beam facilities. The 80 divertor modules were installed in EAST in 2014 and results of the first commissioning are presented in this paper.

EFFECT OF WORKING FLUID, FILLING RATIO AND NUMBER OF TURNS ON PULSATING HEAT PIPE THERMAL PERFORMANCE

Pulsating heat pipe’s (PHP) are one of the alternatives to conventional heat transfer technologies. First part of this paper, titled: thermohydrodynamic behavior of methanol charged closed loop pulsating heat pipe has given information about thermo-hydrodynamic operational characteristics such as; bubble nucleation and collapse, bubble agglomeration and pumping action, flow regime changes, pressure/temperature perturbations, dynamic instabilities, meta-stable non-equilibrium conditions etc. in the PHP. Present paper, which is an extension of the previous work, it presents some more thermal results to highlight the effect of; thermo-physical properties of working fluid, filling ratio and number of turns on thermal performance of PHP. Three different PHP loop has been made from six, four and two parallel glass tubes (i.e. three turns, two turns and one turn at evaporator section) forming adiabatic section, interconnected alternately by copper U tubes, having internal and external diameter 2 mm and 3.06 mm respectively. The length of evaporator, condenser and adiabatic section are 42 mm, 50 mm and 170 mm respectively. The experimentation conducted for different working fluids (water, ethanol, methanol and acetone), different filling ratio’s (30%FR, 50%FR and 70%FR) and different number of turns (one, two and three turns). The motto of present research is to understand the thermal performance in terms of thermal resistance of PHP in details. The result shows that, thermal resistance for all working fluid PHP’s rapidly decreases with increasing heating power up to 32W. For low heating power, working fluid (acetone) which has lower boiling temperature is best, but it cannot give the service for higher heating power. Two turn PHP loop with methanol 50% volumetric filling ratio at more than 32W heating power with one directional flow circulation is the optimum operating condition of present research.

RETRACTED: Experimental study on the thermal management of high-power LED headlight cooling device integrated with thermoelectric cooler package

abstract In view of the characteristics of high power light-emitting diodes (LEDs), such as strict junction temper-ature (T j ) control, the enhanced cooling models based on the thermoelectric cooler (TEC) were presentedto meet the thermal demand of high-power LED headlight. The cooling performance of different devices(air cooling & TEC, liquid cooling & TEC) was evaluated and compared by measuring the LED case tem-perature. Details of the heat transfer performance, particularly, the start-up performances of the TECcooler, as well as the influence of the fan rotate speed or liquid velocity on the system thermal perfor-mance were obtained. It was found that the thermal performance had been elevated dramatically dueto the reduction of the hot side temperature, and the thermoelectric cooler was more sensitive to theexternal fan speed or liquid velocity than purely air cooling or liquid cooling. In addition, the optimal cur-rent for air cooling & TEC was 3A, and 5A for liquid cooling + TEC. Investigations of the simulated ambienttemperature on junction temperature, forward voltage, and output light were conducted. Results indi-cated that the case temperature changed linear basically with the increase in heating power or the sim-ulated ambient temperature. When the ambient temperature was within its severe level (60–65 C), thejunction temperature could be calculated to 59.5 C, and the corresponding output light was 1607.3 lm. 2015 Elsevier Ltd. All rights reserved.

Thermal Model Design and Analysis of High-Power LED Headlamp Cooling Device Based on the Thermoelectric Effect

In view of the characteristics of high-power light-emitting diodes (LEDs), such as strict junction temperature ( $T_{j})$ control, the enhanced cooling models based on the thermoelectric cooler (TEC) were presented to meet the thermal demand of high-power LED headlight. The cooling performance of different devices (air cooling and TEC, and liquid cooling and TEC) was evaluated and compared by measuring the LED case temperature. The details of the heat transfer performance, particularly, the startup performances of the TEC cooler as well as the influence of the fan rotate speed or liquid velocity on the system thermal performance, were obtained. It was found that the thermal performance had been elevated dramatically due to the reduction in hot-side temperature, and the TEC was more sensitive to the external fan speed or liquid velocity than purely air cooling or liquid cooling. In addition, the optimal current for air cooling and TEC was 3 and 5 A for liquid cooling + TEC. The investigations of the simulated ambient temperature on junction temperature, forward voltage, and output light were conducted. The results indicated that the case temperature changed linearly basically with the increase in heating power or the simulated ambient temperature. When the ambient temperature was within its severe level (60 °C–65 °C), the junction temperature could be calculated to 59.5 °C, and the corresponding output light was 1607.3 lm.

Joule heating-induced coexisted spin Seebeck effect and spin Hall magnetoresistance in the platinum/Y3Fe5O12 structure

Spin Seebeck effect (SSE) and spin Hall magnetoresistance (SMR) are observed simultaneously in the Pt/Y3Fe5O12 hybrid structure when thermal gradient is produced by Joule heating. According to their dependences on applied current, these two effects can be separated. Their dependence on heating power and magnetic field is systematically studied. With the increase of heating power, the SSE enhances linearly, whereas the SMR decreases slowly. The origin of the spin currents is further analyzed. The heating power dependences of the spin currents associated with the SSE and the SMR are found to be different.