ANNUAL REPORT of NAKA FUSION RESEARCH ESTABLISHMENT from Aprim, 1994 to March31,1995
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JAERI-Review—95-021 : JP9602221 ANNUAL REPORT OF NAKA FUSION RESEARCH ESTABLISHMENT from ApriM, 1994 to March31,1995 November 1995 Naka Fusion Research Establishment Japan Atomic Energy Research Institute 27lb - HA, (1=319-11 ^ This reports are issued irregularly. Inquiries about availability of the reports should be addressed to Information Division Department of Technical Information, Japan Atomic Energy Research Institute, Tokaimura, Naka-gun, Ibaraki- ken 319-11, Japan. © Japan Atomic Energy Research Institute, 1995 tl * Mi -T- h JAERI-Review 95-021 Annual Report of Naka Fusion Research Establishment from April 1, 1994 to March 31, 1995 Naka Fusion Research Establishment Japan Atomic Energy Research Institute Naka-machi, Naka-gun, Ibaraki-ken (Received October 27, 1995) Research and development activities at Naka Fusion Research Establishment, JAERI, are reported for the period from April 1, 1994 to March 31, 1995. The main objectives of the JT-60 experiments are: confinement improvement, impurity control and divertor studies, steady-state studies, and energetic particle physics. In FY 1994 the highest fusion-triple-product of 2I 3 1.2Xi0 m~ • s • keV • was marked in high-£p H-mode plasma through the optimization of target plasma, heating profile and first wall condition. Regarding steady operation, the triple fusion product of 4.4x1020nr3 • s • keV was sustained for 1.5sec in the ELMy phase of the high-/3p H-mode. Plasma current of 1MA was sustained by non-inductive full current with NB(37$) and with bootstrap current(74$). Helium ash exhaustion, simulated with helium beam injection, demonstrated that wall pumping with the solid target boronization reduced the helium content to one-third of that without boronization and kept constant accumulation^/*) and the helium neutral pressure in the divertor(1 X1CT3 Pa). JFT-2M experiments progressed in the momentum transport study by applying an external helical field and toroidal momentum input with NBI, and also, the boundary plasma study through the introduction of an electric field in the scrape-off layer(SOL) by the divertor biasing. A design of divertor modification for a closed divertor study was carried out with keeping the divertor biasing capability being kept. The study in Plasma Theory and Computation focused on the stability of the Editors: Nagashima T. (Chief), Naito 0., Ogiwara N., Saigusa M., Seki M., Murasawa M., Uehara Y. JAERI-Review 95-021 Toroidal Alfven Eigenmode(TAE) mode as well as analyses of confinement and heating process, MHD equilibrium and stability analyses. Progress in the Dfll -D experiments was obtained in the studies of divertor radiation, advanced tokamak and VH-mode plasma. As for the fusion technology research, activities are focused on the Research and Development (R&D) for ITER EDA: superconducting magnets, neutral beam heating, radio frequency heating, plasma facing components, reactor structure, remote maintenance, shielding branket, tritium processing, tritium safety and fusion safety. In the development of pulsed poloidal field coils, R&D for mass-production of a 9.6ton Nb3Sn conductor was completed and fabrication of a 9.6ton Nb3Sn for 13T was started for ITER. In the development of the DC toroidal field coils, a high performance Nb3Al strand was also developed. The full-sized conductor with 1152 strands successfully produced 39kA at 11.6T and Y.1K. Construction of a MeV-class ion source test facility was completed and the negative H beam was successfully accelerated up to 580keV with a drain current of 110mA for 1sec. Stable, high efficiency, high power generation was demonstrated in a gyrotron with beam energy recovery. By the application of an electron retarding potential, efficiency was enhanced from 30 to 50% at 610kW for 50msec and UOOkW for 4sec at 110GHz. Development of an ITER-relevant 170GHz gyrotron was started. A new tritium removal system using gas separation membranes was studied so as to develop a more compact and cost-effective system for a fusion reactor. A divertor mockup consisting of a flat-plate unidirectional CFC(carbon fiber reinforced carbon composite) armors brazed onto W/Cu composites successfully endured a heat load of 25MW7m2 , 30sec for more than 1000 thermal cycles. Special emergency bearing resistant to large lift forcing was fabricated and tested for the ceramic turbo-viscous pump designed for ITER. The R&D efforts of the reactor structure development focused on the fabrication and testing of a full-scaled section model of double-walled vacuum vessel. Fabricability of the HIPped(Hot Isostatic Pressing) first wall of the ITER shield blanket was investigated through the fabrication of test specimens and partial mockups. Based on the Outline Design approved in March 199U by the ITER Council a sensitivity study was conducted by the new director and JCT in close collaboration with four Home Teams in order to determine the optimum way to achieve a reduction in the cost of ITER while minimizing the impacts regarding its performance margins. Japanese Home Team carried out a part of the ITER design based on task agreements, mainly in the field of vacuum vessel, first wall and blanket, initial assembly, etc. The DREAM tokamak reactor concept was improved focusing on the reactor internals and safety. JAERI-Review 95-021 Keywords: Fusion Research, JAERI, JT-60, JFT-2M, DJI-D, Plasma Physics, Fusion Engineering, Fusion Technology, ITER, Fusion Reactor Design, Annual Report JAERI-Review 95-021 (1994^4 3-1995^3 Mi, s (37%) (74«) (C J F T - 2 MHIft-eii. ^-SiJ^ U * ;l/^^©Mns Rh\ ^14^^^A#f(- «fc (ITER) ©X^tatl-ffiiji (EDA) (^ (R&D) a<ii//e^5o j@m^^°;i/xji^(co^-c(i, i^f±te©Nb3Ai#^^ifl^$n. II.BT, 7. lK(rfc^t39kA©®m*^liE$n/co gi*;l/f-#^t>t:'-A©FSm 580keV"C' 110mA (5l : =f 311-01 its, ±IM mm iv JAERI-Review 95-021 400kW, 4&k\*->J-&'*frXfflifclZi>fii&]Ltzo ITER 3>©raife£EIJ (CFCtm) iZ, (H I P) (ci 1994^3^© I TERS*^lc*SSnfc«S5i!!th»cS-^§, H5KiF3g*<SrUV^0f^t I TE DREAM V 1 NEXT PAGE(S) left BLANK. JAERI-Review 95-021 Contents I. JT-60 Program 1. Overview 1 2. Operation of the JT-60 2 2.1 Tokamak 2 2.2 Control System 3 2.3 Power Supply 4 2.4 Neutral Beam Injection System 5 2.5 Radio-frequency System 6 2.6 Diagnostic System 8 3. Experimental Results and Analysis 11 3.1 Disruptions and Plasma Control 11 3.2 High-jSp Mode and High-/3p H-mode Study 13 3.3 H-mode Studies 15 3.4 Steady-state High Performance 17 3.5 Impurity and Divertor Characteristics 19 3.6 A Study on Fast Ions 21 3.7 LHRF and ICRF Experiments 23 3.8 Development of Fusion Plasma Analysis Codes 25 3.9 Development of the JT-60 Super Upgrade 27 4. Related Developments and Maintenance 29 4.1 Development of a Tritium Monitor Using PIN Diode 29 4.2 New Composite Composed of Boron Carbide and Carbon Fiber with High Thermal Conductivity for the First Wall 29 4.3 Development of a Computer-aided Software Engineering Tool for Sequential Control of Discharges 30 4.4 DSP Application to Fast Parallel Processing in JT-60 Plasma Shape Reproduction 30 4.5 Negative-ion-based Neutral Beam Injection System 31 H. JFT-2M Program 1. Toroidal Confinement Experiments 32 1.1 Overview 32 1.2 Experimental Results 32 1.3 Modification to Closed Divertor 35 vii JAERI-Review 95-021 2. Operation and Related Developments 36 2.1 Operation and Maintenance 36 2.2 Development of Equipment and Apparatus 37 1H. Plasma Theory and Computations 1. Introduction 38 2. Analyses of Confinement and Heating Processes 38 2.1 Self-organized Critical Gradient Transport and Shear Flow Effects on Ion Temperature Gradient Mode in Toroidal Plasmas 38 2.2 Particle Simulation Study of the Toroidal Ion Temperature Gradient Mode in Shear Flow Plasma and a Comparison with Theory • 38 2.3 Differences in Global Mode-structure between Toroidal Alfven Eigenmode and Drift-type Mode 39 3. MHD Equilibrium and Stability Analyses U0 3.1 Eigenvalue Method for Computation of Outer Region Matching Data • 40 3.2 Optimization of MHD Stability in Steady-state Tokamak Reactor : SSTR 40 3.3 Beta Limit Analysis of ITER Plasma with qo=1 41 3.4 Stabilizing Effect of Local Heating on Tearing Mode 41 4. Analyses of Burning Plasma in Tokamaks 41 4.1 Relaxation of Sawtooth Stability Criterion upon Magnetic Shear due to Alpha Particle Pressure 42 4.2 TAE Mode Stability of Steady-state Plasma in JT-60U 42 IV- Cooperative Program on DIH"D (Doublet-H) Experiment 1. Introduction 43 2. Highlights of FY 1994 Research Results 43 2.1 Divertor Radiation Research 43 2.2 Advanced Tokamak Research 44 2.3 Tokamak Physics Studies 45 V• Technology Development 1. Outline 46 2. Fueling/Pumping and Vacuum Technology 47 2.1 Development of Railgun Pellet Accelerator 47 2.2 Progress in R&D of Pumping 48 2.3 Vacuum Technology 49 3. Superconducting Magnet Development 50 3.1 Introduction 50 JAERI-Review 95-021 3.2 Central Solenoid(CS)Model Coil 50 3.3 Development of Nb3Al 53 3.4 CS Model Coil Test Facility(CSTF) 54 4. Beam Technology 56 4.1 Introduction 56 4.2 Negative Ion Beam Technology 56 4.3 Application of High Current Positive Ion Beam Technology 59 5. RF Heating Technology 60 5.1 Introduction 60 5.2 Developments of High Power Gyrotron and ECH Components 60 5.3 Development of ICRF and LHRF Launchers 61 5.4 Millimeter Wave Free Electron Laser 62 6. Tritium Technology 63 6.1 Research Activity under US-Japan Collaboration 63 6.2 Development of Tritium Processing Technology in TPL 64 6.3 Development of Tritium Safety Technology 65 6.4 Operation of Tritium Safety System in TPL 67 6.5 Tritium Transportation Using an International Transport Package.