Abstract EAST has demonstrated its capability of long pulse operation using RF heating （LHCD and ICRF） in past experiments. One key issue to realize the long pulse H-mode expert- meats is to sustain the plasma curre...Abstract EAST has demonstrated its capability of long pulse operation using RF heating （LHCD and ICRF） in past experiments. One key issue to realize the long pulse H-mode expert- meats is to sustain the plasma current for steady state operation. Based on the calculations of the transport code ONETWO and its coupled RF code GENRAY, two scenarios have been proposed to achieve the 10 s H-mode plasma with Ip=400 kA, 〈 ne 〉=4.5×1019 m-a, βN=2, and the 100 s H-mode plasma with Ip=280 kA, 〈 ne 〉=3.5×1019 m-a, βN=1.8 recently. The current drive of lower hybrid wave is an important issue in the two scenarios. An experimental result on lower hybrid current drive in H-mode plasmas on EAST is also presented.展开更多
Neoclassical tearing mode (NTM) can degrade plasma confinement or even cause disruptions in existing tokamaks. Stabilization of the NTMs by radio frequency (rf) current is investigated by the modified Rutherford equat...Neoclassical tearing mode (NTM) can degrade plasma confinement or even cause disruptions in existing tokamaks. Stabilization of the NTMs by radio frequency (rf) current is investigated by the modified Rutherford equation (MRE) in this paper. In a range of parameters, the required rf current for mode stabilization is obtained, which is linearly proportional to the bootstrap current density for both modulated current drive (MCD) and non-modulated current drive (NMCD), linearly (quadratically) to the radial width of the rf current for MCD (NMCD), and quadratically to the radial deviation of the rf current from the rational surface for both MCD and NMCD.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
An RF compensated cylindrical Langmuir probe system has been developed and used to characterize an RF capacitive two temperature plasma discharge in a stochastic mode. The novelty of the work presented here is the use...An RF compensated cylindrical Langmuir probe system has been developed and used to characterize an RF capacitive two temperature plasma discharge in a stochastic mode. The novelty of the work presented here is the use of the driven electrode （cathode） without ground shield. Measurements of the electron energy distribution function （EEDF） and plasma parameters were achieved under the following conditions： 50 W of RF power and 5× 10-2 mbar of argon pressure. The probe measurements are performed at 3 cm above the electrode and the probe was shifted radially （r direction） from the center （r = 0 cm） of the inter-electrodes region towards the chamber wall （R = 10.75 cm）. The results show that the EEDF is bi-Maxwellian and its shape remains the same through the scanned region. The farther the probe from the central region, the lower the EEDF maximum. The plasma density is observed to decrease according to a Gaussian profile along the radial direction and falls to 50% of its maximum when close to the cathode edge （r = 5.5 cm）. At the same time the effective electron temperature remains constant for r〈4 cm and increases for r≥4 cm. The high-temperature and low-temperature electrons＇ densities and temperatures are also discussed in the article.展开更多
Polymer ethylene oxide （PEO） functional films can be used as a material for biocompatible research. In this paper, we investigated the structures of PEO-like films polymerized on Si surface with diethlyene glycole d...Polymer ethylene oxide （PEO） functional films can be used as a material for biocompatible research. In this paper, we investigated the structures of PEO-like films polymerized on Si surface with diethlyene glycole dimethyl ether （DEGDME） as the precursor and Ar as the dilution gas by plasma enhanced chemical vapor deposition （PECVD）. And the pulse plasma model was employed to polymerize the functional films. The chemical structure of the coatings was investigated by Fourier transform inference （FTIR） and X-ray photoelectron spectroscopy （XPS）. The results indicate that PEO-like structure films can be polymerized by DEGDME/Ar plasma. The concentration of C-O functional groups polymerized in the long plasma-off time was much higher than that in the short plasma-off time. With the same discharge parameters, moreover, the C-O ratio in polymers increased with a higher injected power.展开更多
We propose an input protection scheme composed of thyristor devices only without using a clamp NMOS device in order to minimize the area consumed by a pad structure in CMOS RF ICs. For this purpose, we suggest low-vol...We propose an input protection scheme composed of thyristor devices only without using a clamp NMOS device in order to minimize the area consumed by a pad structure in CMOS RF ICs. For this purpose, we suggest low-voltage triggering thyristor protection device structures assuming usage of standard CMOS processes, and attempt an in-depth comparison study with a conventional thyristor protection scheme incorporating a clamp NMOS device. The comparison study mainly focuses on robustness against the HBM ESD in terms of peak voltages applied to gate oxides in an input buffer and lattice heating inside protection devices based on DC and mixed-mode transient analyses utilizing a 2-dimensional device simulator. We constructed an equivalent circuit for the input HBM test environment of the CMOS chip equipped with the input ESD protection devices. And by executing mixed-mode simulations including up to four protection devices and analyzing the results for five different test modes, we attempt a detailed analysis on the problems which can occur in real HBM tests. We figure out strength of the proposed thyristor-only protection scheme, and suggest guidelines relating the design of the protection devices and circuits.展开更多
In this work, physical models of neoclassical tearing modes （NTMs） including bootstrap current and multiple modulated electron cyclotron current drive model are applied. Based on the specific physical problems durin...In this work, physical models of neoclassical tearing modes （NTMs） including bootstrap current and multiple modulated electron cyclotron current drive model are applied. Based on the specific physical problems during the suppression of NTMs by driven current, this work compares the efficiency of continuous and modulated driven currents, and simulates the physical processes of multiple modulated driven currents on suppressing rotating magnetic island. It is found that when island rotates along the poloidal direction, the suppression ability of continuous driven current can be massively reduced due to current deposition outside the island separatrix and reverse deposition direction at the X point, which can be avoided by current drive modulation. Multiple current drive has a better suppressing effect than single current drive. This work gives realistic numerical simulations by optimizing the model and parameters based on the experiments, which could provide references for successful suppression of NTMs in future advanced tokamak such as international thermonuclear experimental reactor.展开更多
The tokamak plasma flows induced by the local radio frequency （RF） forces in the core region are analyzed. The effective components of local RF forces are composed of the momentum absorption term and the resonant pa...The tokamak plasma flows induced by the local radio frequency （RF） forces in the core region are analyzed. The effective components of local RF forces are composed of the momentum absorption term and the resonant parallel momentum transport term （i.e. the parallel component of the resonant ponderomotive forces）. Different momentum balance relations are em- ployed to calculate the plasma flows depending on different assumptions of momentum transport. With the RF fields solved from RF simulation codes, the toroidal and poloidal flows by these forces under the lower hybrid current drive and the mode conversion ion cyclotron resonance heating on EAST-like plasmas are evaluated.展开更多
基金supported by the National Magnetic Confinement Fusion Program of China(Nos.2014GB106000,2014GB106001,and2014GB106003)National Natural Science Foundation of China(Nos.11275234,11321092,11305215,11305208,11405214)CAS Hefei Center for Scientific Research Program of China(No.2015SRG-HSC010)
文摘Abstract EAST has demonstrated its capability of long pulse operation using RF heating （LHCD and ICRF） in past experiments. One key issue to realize the long pulse H-mode expert- meats is to sustain the plasma current for steady state operation. Based on the calculations of the transport code ONETWO and its coupled RF code GENRAY, two scenarios have been proposed to achieve the 10 s H-mode plasma with Ip=400 kA, 〈 ne 〉=4.5×1019 m-a, βN=2, and the 100 s H-mode plasma with Ip=280 kA, 〈 ne 〉=3.5×1019 m-a, βN=1.8 recently. The current drive of lower hybrid wave is an important issue in the two scenarios. An experimental result on lower hybrid current drive in H-mode plasmas on EAST is also presented.
文摘Neoclassical tearing mode (NTM) can degrade plasma confinement or even cause disruptions in existing tokamaks. Stabilization of the NTMs by radio frequency (rf) current is investigated by the modified Rutherford equation (MRE) in this paper. In a range of parameters, the required rf current for mode stabilization is obtained, which is linearly proportional to the bootstrap current density for both modulated current drive (MCD) and non-modulated current drive (NMCD), linearly (quadratically) to the radial width of the rf current for MCD (NMCD), and quadratically to the radial deviation of the rf current from the rational surface for both MCD and NMCD.
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.
文摘An RF compensated cylindrical Langmuir probe system has been developed and used to characterize an RF capacitive two temperature plasma discharge in a stochastic mode. The novelty of the work presented here is the use of the driven electrode （cathode） without ground shield. Measurements of the electron energy distribution function （EEDF） and plasma parameters were achieved under the following conditions： 50 W of RF power and 5× 10-2 mbar of argon pressure. The probe measurements are performed at 3 cm above the electrode and the probe was shifted radially （r direction） from the center （r = 0 cm） of the inter-electrodes region towards the chamber wall （R = 10.75 cm）. The results show that the EEDF is bi-Maxwellian and its shape remains the same through the scanned region. The farther the probe from the central region, the lower the EEDF maximum. The plasma density is observed to decrease according to a Gaussian profile along the radial direction and falls to 50% of its maximum when close to the cathode edge （r = 5.5 cm）. At the same time the effective electron temperature remains constant for r〈4 cm and increases for r≥4 cm. The high-temperature and low-temperature electrons＇ densities and temperatures are also discussed in the article.
文摘Polymer ethylene oxide （PEO） functional films can be used as a material for biocompatible research. In this paper, we investigated the structures of PEO-like films polymerized on Si surface with diethlyene glycole dimethyl ether （DEGDME） as the precursor and Ar as the dilution gas by plasma enhanced chemical vapor deposition （PECVD）. And the pulse plasma model was employed to polymerize the functional films. The chemical structure of the coatings was investigated by Fourier transform inference （FTIR） and X-ray photoelectron spectroscopy （XPS）. The results indicate that PEO-like structure films can be polymerized by DEGDME/Ar plasma. The concentration of C-O functional groups polymerized in the long plasma-off time was much higher than that in the short plasma-off time. With the same discharge parameters, moreover, the C-O ratio in polymers increased with a higher injected power.
文摘We propose an input protection scheme composed of thyristor devices only without using a clamp NMOS device in order to minimize the area consumed by a pad structure in CMOS RF ICs. For this purpose, we suggest low-voltage triggering thyristor protection device structures assuming usage of standard CMOS processes, and attempt an in-depth comparison study with a conventional thyristor protection scheme incorporating a clamp NMOS device. The comparison study mainly focuses on robustness against the HBM ESD in terms of peak voltages applied to gate oxides in an input buffer and lattice heating inside protection devices based on DC and mixed-mode transient analyses utilizing a 2-dimensional device simulator. We constructed an equivalent circuit for the input HBM test environment of the CMOS chip equipped with the input ESD protection devices. And by executing mixed-mode simulations including up to four protection devices and analyzing the results for five different test modes, we attempt a detailed analysis on the problems which can occur in real HBM tests. We figure out strength of the proposed thyristor-only protection scheme, and suggest guidelines relating the design of the protection devices and circuits.
基金supported by National Natural Science Foundation of China(Grand Nos.11605021,11375039 and 11275034)Natural Science Foundation of Liaoning Province(Grand No.201601074)supported by'the Fundamental Research Funds for the Central Universities'(Grand Nos.3132016128 and 3132014328)
文摘In this work, physical models of neoclassical tearing modes （NTMs） including bootstrap current and multiple modulated electron cyclotron current drive model are applied. Based on the specific physical problems during the suppression of NTMs by driven current, this work compares the efficiency of continuous and modulated driven currents, and simulates the physical processes of multiple modulated driven currents on suppressing rotating magnetic island. It is found that when island rotates along the poloidal direction, the suppression ability of continuous driven current can be massively reduced due to current deposition outside the island separatrix and reverse deposition direction at the X point, which can be avoided by current drive modulation. Multiple current drive has a better suppressing effect than single current drive. This work gives realistic numerical simulations by optimizing the model and parameters based on the experiments, which could provide references for successful suppression of NTMs in future advanced tokamak such as international thermonuclear experimental reactor.
基金supported by National Natural Science Foundation of China(Nos.11405218,11325524,11375235 and 11261140327)in part by the National Magnetic Confinement Fusion Science Program of China(Nos.2013GB111002,2013GB112001 and 2013GB112010)the Program of Fusion Reactor Physics and Digital Tokamak with the CAS"One-Three-Five"Strategic Planning
文摘The tokamak plasma flows induced by the local radio frequency （RF） forces in the core region are analyzed. The effective components of local RF forces are composed of the momentum absorption term and the resonant parallel momentum transport term （i.e. the parallel component of the resonant ponderomotive forces）. Different momentum balance relations are em- ployed to calculate the plasma flows depending on different assumptions of momentum transport. With the RF fields solved from RF simulation codes, the toroidal and poloidal flows by these forces under the lower hybrid current drive and the mode conversion ion cyclotron resonance heating on EAST-like plasmas are evaluated.
