In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated...In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.展开更多
Measurements of the total radiated power and its spatial distribution are crucial for fusion research.On the experimental advanced superconducting tokamak(EAST),both the metal foil resistive bolometer and the absolute...Measurements of the total radiated power and its spatial distribution are crucial for fusion research.On the experimental advanced superconducting tokamak(EAST),both the metal foil resistive bolometer and the absolute extreme ultraviolet(AXUV)photodiodes have been used to quantify the radiated power.This article introduces the latest improvement of the bolometer diagnostic system on EAST.It also details the successful design and installation of new divertor AXUV cameras,which are dedicated to the investigation of divertor physics.The shielding components of the bolometer detector have been refined,and the article provides a detailed exposition of the double shielding structures that have been verified as effective in microwave shielding.Additionally,the changes in the radiated power distribution in the divertor region during the plasma detachment process are measured using the divertor AXUV camera.Finally,the radiated power measured by the AXUV detector and metal foil resistive bolometer are compared,and different detector performances are presented.展开更多
In 2021,EAST realized a steady-state long pulse with a duration over 100 s and a core electron temperature over 10 keV.This is an integrated operation that resolves several key issues,including active control of wall ...In 2021,EAST realized a steady-state long pulse with a duration over 100 s and a core electron temperature over 10 keV.This is an integrated operation that resolves several key issues,including active control of wall conditioning,long-lasting fully noninductive current and divertor heat/particle flux.The fully noninductive current is driven by pure radio frequency(RF)waves with a lower hybrid current drive power of 2.5 MW and electron cyclotron resonance heating of 1.4 MW.This is an excellent experimental platform on the timescale of hundreds of seconds for studying multiscale instabilities,electron-dominant transport and particle recycling(plasma-wall interactions)under weak collisionality.展开更多
Hard x-ray(HXR)burst is found during internal crash in the flat top current stage of experimental advanced superconducting tokamak(EAST)discharges and it is caused by fast electrons.The generated electrons during inte...Hard x-ray(HXR)burst is found during internal crash in the flat top current stage of experimental advanced superconducting tokamak(EAST)discharges and it is caused by fast electrons.The generated electrons during internal crashes may be an operational safety issue in advanced tokamaks.During an internal crash,locations of fast electron generation from HXR evolution agree with areas of magnetic reconnection from soft x-ray(SXR)tomographic reconstruction.Further statistical analyses show a 27μs time difference between SXR crashes and HXR bursts,and the agreement between time broadening of HXR bursts and estimated characteristic time of magnetic reconnection in EAST.The magnetic reconnections during internal crash are proved to generate fast electrons,by both spatial and temporal agreements.展开更多
In the 2016 EAST experimental campaign,a steady-state long-pulse H-mode discharge with an ITER-like tungsten divertor lasting longer than one minute has been obtained using only RF heating and current drive,through an...In the 2016 EAST experimental campaign,a steady-state long-pulse H-mode discharge with an ITER-like tungsten divertor lasting longer than one minute has been obtained using only RF heating and current drive,through an integrated control of the wall conditioning,plasma configuration,divertor heat flux,particle exhaust,impurity management,and effective coupling of multiple RF heating and current drive sources at high injected power.The plasma current（Ip - 0.45 MA） was fully-noninductively driven（Vloop 〈 0.0 V） by a combination of-2.5 MW LHW,-0.4 MW ECH and -0.8 MW ICRF.This result demonstrates the progress of physics and technology studies on EAST,and will benefit the physics basis for steady state operation of ITER and CFETR.展开更多
In recent EAST experiments,current profile broadening characterized by reduced internal inductance has been achieved by utilizing radio-frequency current drives(RFCD).In contrast to previous density scan experiments,w...In recent EAST experiments,current profile broadening characterized by reduced internal inductance has been achieved by utilizing radio-frequency current drives(RFCD).In contrast to previous density scan experiments,which showed an outward shift of the current density profile of lower hybrid current drive(LHCD)in higher plasma density,the core electron temperature(T_(e)(0))is found to affect the LHCD current profile as well.According to equilibrium reconstruction,a significant increase in on-axis safety factor(q0)from 2.05 to 3.41 is observed by careful arrangement of RFCD.Simulations using ray-tracing code GENRAY and Fokker–Planck code CQL3D have been performed to thoroughly analyze the LHCD current profile,revealing the sensitivity of the LHCD current profile to T_(e)(0).The LHCD current density tends to accumulate in the plasma core with higher current drive efficiency benefiting from higher T_(e)(0).With a lower T_(e)(0),the LHCD current profile broadens due to off-axis deposition of power density.The sensitivity of the power deposition and current profile of LHCD to T_(e)(0)provides a promising way to effectively optimize current profile via control of the core electron temperature.展开更多
A cylindrical carbon pellet with a size of 1.2L x 1.2φ mm to 1.8L x 1.8φ mm and a velocity of 100 m/s to 300 m/s was injected into large helical device （LHD） for an efficient fueling based on its deeper deposition...A cylindrical carbon pellet with a size of 1.2L x 1.2φ mm to 1.8L x 1.8φ mm and a velocity of 100 m/s to 300 m/s was injected into large helical device （LHD） for an efficient fueling based on its deeper deposition instead of hydrogen gas puffing and ice pellet injection. Electron density increment of Ane = 10^14 cm^-3 is successfully obtained by single carbon pellet injection without plasma collapse. Typical density and temperature of the ablation plasma of the carbon pellet, e.g., 6.5× 10^16 cm^-3 and 2.5 eV for CII, are examined respectively by spectroscopic method. A confinement improvement up to 50% compared to ISS-95 stellarator scaling is clearly observed in a relatively low-density regime of ne = 2 × 10^13 cm^-3 to 4×10^13 cm^-3, and high ion temperature Ti（0） of about 6 keV is also observed with an internal transport barrier at ne = 1.2 × 10^13 cm^-3. In particular, the improvement in the ion temperature largely exceeds that observed in hydrogen gas-puffed discharges, which typically ranges below 3 keV.展开更多
文摘In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.
基金supported by the National MCF Energy R&D Program of China(Nos.2022YFE03040003 and 2019YFE03010003).
文摘Measurements of the total radiated power and its spatial distribution are crucial for fusion research.On the experimental advanced superconducting tokamak(EAST),both the metal foil resistive bolometer and the absolute extreme ultraviolet(AXUV)photodiodes have been used to quantify the radiated power.This article introduces the latest improvement of the bolometer diagnostic system on EAST.It also details the successful design and installation of new divertor AXUV cameras,which are dedicated to the investigation of divertor physics.The shielding components of the bolometer detector have been refined,and the article provides a detailed exposition of the double shielding structures that have been verified as effective in microwave shielding.Additionally,the changes in the radiated power distribution in the divertor region during the plasma detachment process are measured using the divertor AXUV camera.Finally,the radiated power measured by the AXUV detector and metal foil resistive bolometer are compared,and different detector performances are presented.
基金the National Key R&D Program of China(No.2022YFE03010003)National Natural Science Foundation of China(No.12275309).
文摘In 2021,EAST realized a steady-state long pulse with a duration over 100 s and a core electron temperature over 10 keV.This is an integrated operation that resolves several key issues,including active control of wall conditioning,long-lasting fully noninductive current and divertor heat/particle flux.The fully noninductive current is driven by pure radio frequency(RF)waves with a lower hybrid current drive power of 2.5 MW and electron cyclotron resonance heating of 1.4 MW.This is an excellent experimental platform on the timescale of hundreds of seconds for studying multiscale instabilities,electron-dominant transport and particle recycling(plasma-wall interactions)under weak collisionality.
文摘Hard x-ray(HXR)burst is found during internal crash in the flat top current stage of experimental advanced superconducting tokamak(EAST)discharges and it is caused by fast electrons.The generated electrons during internal crashes may be an operational safety issue in advanced tokamaks.During an internal crash,locations of fast electron generation from HXR evolution agree with areas of magnetic reconnection from soft x-ray(SXR)tomographic reconstruction.Further statistical analyses show a 27μs time difference between SXR crashes and HXR bursts,and the agreement between time broadening of HXR bursts and estimated characteristic time of magnetic reconnection in EAST.The magnetic reconnections during internal crash are proved to generate fast electrons,by both spatial and temporal agreements.
基金supported by the National Magnetic Conlinement Fusion Science Program of China(Nos.2015GB102000 and 2015GB103000)
文摘In the 2016 EAST experimental campaign,a steady-state long-pulse H-mode discharge with an ITER-like tungsten divertor lasting longer than one minute has been obtained using only RF heating and current drive,through an integrated control of the wall conditioning,plasma configuration,divertor heat flux,particle exhaust,impurity management,and effective coupling of multiple RF heating and current drive sources at high injected power.The plasma current（Ip - 0.45 MA） was fully-noninductively driven（Vloop 〈 0.0 V） by a combination of-2.5 MW LHW,-0.4 MW ECH and -0.8 MW ICRF.This result demonstrates the progress of physics and technology studies on EAST,and will benefit the physics basis for steady state operation of ITER and CFETR.
基金supported by the National MCF Energy R&D Program of China (No. 2019YFE0304000)National Natural Science Foundation of China (Nos. 12005262 and 11975274)+3 种基金the Anhui Provincial Natural Science Foundation (No. 2108085J06)the Users with Excellence Program of Hefei Science Center CAS (Nos. 2021HSC-UE018 and 2020HSC-UE011)the External Cooperation Program of Chinese Academy of Sciences (No. 116134KYSB20180035)the Science Foundation of Institute of Plasma Physics, Chinese Academy of Sciences (No. DSJJ-2021-04)
文摘In recent EAST experiments,current profile broadening characterized by reduced internal inductance has been achieved by utilizing radio-frequency current drives(RFCD).In contrast to previous density scan experiments,which showed an outward shift of the current density profile of lower hybrid current drive(LHCD)in higher plasma density,the core electron temperature(T_(e)(0))is found to affect the LHCD current profile as well.According to equilibrium reconstruction,a significant increase in on-axis safety factor(q0)from 2.05 to 3.41 is observed by careful arrangement of RFCD.Simulations using ray-tracing code GENRAY and Fokker–Planck code CQL3D have been performed to thoroughly analyze the LHCD current profile,revealing the sensitivity of the LHCD current profile to T_(e)(0).The LHCD current density tends to accumulate in the plasma core with higher current drive efficiency benefiting from higher T_(e)(0).With a lower T_(e)(0),the LHCD current profile broadens due to off-axis deposition of power density.The sensitivity of the power deposition and current profile of LHCD to T_(e)(0)provides a promising way to effectively optimize current profile via control of the core electron temperature.
文摘A cylindrical carbon pellet with a size of 1.2L x 1.2φ mm to 1.8L x 1.8φ mm and a velocity of 100 m/s to 300 m/s was injected into large helical device （LHD） for an efficient fueling based on its deeper deposition instead of hydrogen gas puffing and ice pellet injection. Electron density increment of Ane = 10^14 cm^-3 is successfully obtained by single carbon pellet injection without plasma collapse. Typical density and temperature of the ablation plasma of the carbon pellet, e.g., 6.5× 10^16 cm^-3 and 2.5 eV for CII, are examined respectively by spectroscopic method. A confinement improvement up to 50% compared to ISS-95 stellarator scaling is clearly observed in a relatively low-density regime of ne = 2 × 10^13 cm^-3 to 4×10^13 cm^-3, and high ion temperature Ti（0） of about 6 keV is also observed with an internal transport barrier at ne = 1.2 × 10^13 cm^-3. In particular, the improvement in the ion temperature largely exceeds that observed in hydrogen gas-puffed discharges, which typically ranges below 3 keV.
