The Circulating Current Analysis and Parameter Design of Interphase—Reactor of HT—7U Toroidal Power Supply

This paper analyzes the circulating current which is produced by HT-7U superconducting toroidal power supply-two sets of two-reverse-star converter with an interphase-reactor in parallel running on the basis of the output voltage mathematical equation of three-phaase semi-wave converter circuit.A new iden of omitting interphase-reactor between two converters is proposed,and the parameter design of interphase-reactor of HT-7 toroidal power supply is presented.Simulated results demonstrate the validity of this new project.     

The Study of Heat Pulse Propagation on HT—7 Tokamak

The propagation of heat pulses originating from sawtooth activity has been studied on the HT-7 tokamak.Two theoretical models are used for determining electron heat diffusivity from the experimental data measured by a diagnostic system of soft x-ray diode-array.The results show that one model caaled dipole model is more suitable for HT-7 tokamak.In order to improve the signal-to-noise(S/N) ratio of the original signals,over a few tens of sawteeth are averaged to generatc nicc wavcforms.The apace-time evolution is found to be diffusive in character,which is consistent with the theoretical model.The electron heat diffusivity determined from heat pulse propagation is larger than determined from background plasma power balance.The variation of Xe in different discharge phases has been also discussed.     

Poloidal Field Control for the HT—7U Superconducting Tokamak

Controlling the poloidal field(PF) in the HT-7U superconducting tokamak is critical to the realization of the mission of advanced tokamak research.Plasma start-up,plasma position,shape,current control and plasma shape reconstruction have been performed as a part of its design process.The PF coils have been designed to produce a wide range of plasmas,Plasma start-up can be achieved for multiple conditions.Fast controlling coils for plasma position inside the vacuum vessel are sued for controloling the plasma vertical position on a short timescale.The PF coils control the plasma current and shape on a slower timescale,VXI(VME bus extensions for Instrumentation)Bus system and DSP(Digital Signal Processor is a basic unit of the feedback control system),the response time of which is about(2-4)ms.The basic unit of this system ,the shape-controlling algorithms of a few critical points on plasma boundary and real-time equilibrium fitting(RTEFIT)will be described in this paper.     

Recent Experimental Progress in the HT—7 Tokamak

Recent experimental campaign in the HT-7 tokamak was scheduled to be ran from November 2002to March 31,2003,During which various issues were in vestgated on geting high electron temperature,long pulse discharges and high performance plasma under quasi-steady-state condition.New systems including LHCD launcher,cryogenic compressor,real-time ploidal control,water-cooled toroidal belt limiter,ferretic liner and several diagnostics were installed and operated to satisfy long-pulse operation requirements.The maximum total injected power was over 1 MW and the longest discharge duration was near to 64 s。     

Temperature Distribution at the Lower Hybrid Wave Antenna on the Superconducting Tokamak HT－7

The radiation constant of the plasma and the temperature distribution at the Lower Hybrid Wave(LHW) antenna on the superconducting tokamak HT-7 axe calculated from the engineering point of view and the result provides an important reference to the design of a new antenna.     

Superconducting Busline Design for HT—7U Tokamak

Superconducting (SC) tokamak HT-7U has seven pairs of buslines connecting toroidal/Poloidal coils and the current leads,These SC buslines(SCBLs) share a common cryostat and are made of the calbe in conduit conductors(CICCs) arranged as a decoupling configuration.In order to reduce the heat loads conducted from the seven current leads with a capacity of 15kA during the magnets cooldown.the buslines with a much lower thermal conduction were employed in comparison with the current leads,and a special cooling loop was designed.     

Structural Analysis of Central Solenoid for HT—7U

The central solenoid(CS) composed of cable-in-conduit(CIC) type conductor is an important part of the HT-7U device,The CS coils can be considered from the viewpoint of micromechanics as a compostie material.And then,the residual stiffness is computed according to the micro-damage modeling of continuum damage mechanics,These material properties have been used as input data for finite element method(FEM) analysis.In this paper the computational analysis of the stress and the displacement on the central solenoid are made by the finite element analysis system COSMOS/M2.0 under operating temperature.According to the analytical results.the CS coils are all satisfied with designed safety criteria.     

Recent Progress of HT-7U Superconducting Tokamak

HT-7U is a superconducting tokamak. which is being constructed in Institute of Plasma Physics, Chinese Academy of Sciences. The mission of the HT-7U project is to develop a scientific and engineering basis of the steady state operation of advanced tokamak.The engineering design of the device has been optimized. The R&D program is going on. Short samples of the conductor and a CS model coil were tested. All the TF and PF coils will be manufactured and tested in Institute of Plasma Physics. Therefore, a 600-meter long jacketing line for cable-in-conduit conductors along with two winding machines, a set of VPI equipment and a test facility for the TF and PF coils are ready in ASIPP now. In this paper, the recent progress of the HT-7U is described.     

Calculation and Analysis of Magnetic Field Pattern for TEXT—U Equipment

In this paper,the toroidal field B of a tokamak produced by separate coils has been calculated from the basic electrodynamic theory.As an example,the toroidal magnetic field B(R) in TEXT-U tokamak is plotted.and the curve is fitted well to the analysis formula B(R)=B0R0/R with a precision of several percents.     

The Experiment of Modulated Toroidal Current on HT-7 and HT-6M Tokamak

The Experiments of Modulated Toroidal Current were done on the HT-6M tokamak and HT-7 superconducting tokamak. The toroidal current was modulated by programming the Ohmic heating field. Modulation of the plasma current has been used successfully to suppress MHD activity in discharges near the density limit where large MHD m = 2 tearing modes were suppressed by sufficiently large plasma current oscillations. The improved Ohmic confinement phase was observed during modulating toroidal current (MTC) on the Hefei Tokamak-6M (HT-6M) and Hefei superconducting Tokamak-7 (HT-7). A toroidal frequency-modulated current, induced by a modulated loop voltage, was added on the plasma equilibrium current. The ratio of A.C. amplitude of plasma current to the main plasma current △Ip/Ip is about 12% ～ 30%. The different formats of the frequency-modulated toroidal current were compared.     

Design of Magnetic Measurement System on SUNIST Spherical Tokamak

A magnetic measurement system consisting of magnetic probes and flux loops for spherical tokamak SUNIST, is uniquely designed due to the strongly shaped plasma cross section and the narrow space near the central solenoid. Plasma equilibrium reconstruction with the current filament method is performed to determine the number and positions of the magnetic probes and flux loops, as well as their design precision required.     

Design of the Cryostat for HT—7U superconducting Tokamak

The cryostat of HT-7U tokamak is a large vacuum vessel surrounding the entire basic machine with a cylindrical shell,a dished top and a flat bottom.The main function of HT-7U cryostat is to provide a thermal barrier between an ambient temperature test hall and a liquid helium-cooled superconducting magnet.The loads applied to the cryostat are from sources of vacuum pressure,dead weight,seismic events and electromagnetic forces originated by eddy currents.It also provides feed-through penetrations for all the conecting elements inside and outside the cryostat.The main material selected for the cryostat is stainless steel 304L.The structural analyses including buckling for the cryostat vessel under the plasma operation condition have been carried out by using a finite element code.Stress analysis results show that the maximum stress intensity was below the allowable value.In this paper,the structural analyses and design of HT-7U cryostat are emphasized.     

HT-7U超导托卡马克冷质部件支撑结构分析

介绍一种叠板式柔性支撑结构以及该结构用于HT 7U超导托卡马克装置中的特点 ,并介绍了有限元分析法在支撑系统分析中的应用 ,计算在各种载荷作用下支撑结构在的极限应力及应力分布状况 ,为结构设计的各项参数提供必要的理论依据     

Design of the Magnetic Field for HT-7U Tokamak

1. Main parameters ofHT-7U deviceThe scientific cession of the HT－7U(HefeiTOkamak-7 Upgrade ), being a next generation advanced tokamak, is to study physical issues on thesteady-state operation of a non-burning plasma. The'. -.engineering mission of the HT-7U tokamak is to establish the technology basis of full superconductingtokamaks for the future reactor. The HT-7U toka-mak will have a long pulse (60 ~ 1000 s ) capability,a flexible PF system, an auxiliary heating and current drive …     

Magnetic Sensorless Sensing of Plasma Position in the Superconducting Tokamak HT-7

Magnetic sensorless sensing experiments of the plasma horizontal position have been carried out in the superconducting tokamak HT-7. The horizontal position is calculated from the vertical field coil current and voltage without using signals of magnetic probes placed nearby a plasma. The calculations are focused on the ripple frequency component of the power supply.There is no drift problem with the time integration of magnetic probe signals. The error of the derived plasma position is lower than 2% of the plasma minor radius.     

The Design of Circuit for Checking Short in HT-7U Superconducting Tokamak Device

1.IntroductionHT-7Usuperconductingtokamakisanationalsci-entificresearchprojectofChina,inwhichthislargefusionexperimentdevicewillbebuiltattheInstituteofPlasmaPhysicsofChineseAcademyofSciences.ThemissionofHT-7Uistodevelopascientificbasisforacontinuouslyoperatingtokamakfusionre-actor,withasteady-stateandextremelylong-pulseoperation.AsHT-7Uisafullsuperconductingtokamakdevice,itisimportanttokeeptheHT-7Ude-viceasafeoperation.BeforetheoperationofHT-7Udevice,theoperatorhastogettheoperationalp…     

Design of the Pumping Stations and the Gas Puffing Systems for the Superconducting Tokamak HT-7U

1. IntroductionHT-7U is an upgrade device for the superconducting' tokamak HT--7 in Hefei, C,hina." It will be t.helargest TOkamak in China, with a major radius of l.7m and a minor cross section of 0.6 m x 0.4 m. Thetypical plasma pulse length will be 1000 s, and thetoroidal superconducting magnetic field on plasmaaxis will be 3.5 T [1].The parameters of the vacuum system of TokamakTore Supra in France and Tokamak JET in the U.Kare taken as our design references. The volume ofJET tor…     

Using Poloidal Flux as Feedback Control Signal for Injected Power of LHCD in Long Pulse Discharge on HT-7 Tokamak

Long pulse discharge is one of the important goals of HT-7 superconducting tokamak experiments. For ITER （International Thermonuclear Experimental Reactor） or a tokamak reactor, carrying out a steady operation is one of the main techniques. For long pulse discharges on HT-7 the poloidal flux is used as the feedback signal to control the injected power of LHCD （Low Hybrid Current Drive） system. Experimental results are presented.     

Simulation Study of Heat Flux Deposition Pattern on the Surface of HT-7 Toroidal Limiters

The heat flux deposition pattern on the toroidal limiters installed in HT-7 was simulated with ANSYS code. The simulation model was established with the ripple of the magnetic field. The heat deposition pattern and temperature distribution on the surface of the toroidal linfiters were obtained. A comparison of the results obtained with and without the shaped tiles, used to reduce the heat flux on the leading edge of the limiters, was made. The maximum heat load allowed at the leading edge was about 1.8 MW/m2 because of the poor power removing capacity on the ends of the limiters. This approach can also be applied to other devices with a limiter configuration in a circular cross-section shape.