[en] This report explains briefly the physical aspect and outline of the Heliotron E device. The index is as follows. (1) Outline of the Heliotron E (a) machine parameters, (b) physical aspects and objects, (c) time schedule, (d) power supply. (2) Research and development. (3) Pictures of the real size model

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[en] Conceptual design of blanket and divertor for a force free helical reactor (FFHR) is presented. The DEMO relevant FFHR is heliotron type helical reactor having super conducting helical and poloidal coils based on the Large Helical Device (LHD) which is now under construction in NIFS. The main features of FFHR are (1) force free configuration of helical coils to reduce the total structural mass required for magnetic energy, (2) plasma operation with no current disruptions, (3) steady-state operation with a small fraction of the recirculating power. For the goal of a self-ignited D-T reactor of 3 GW thermal output, the design parameters for FFHR are investigated under the LHD scaling for energy confinement and density limit. In particular, to satisfy the reactor lifetime of 30 years, the engineering issues in FFHR are discussed by focusing on the following aspects; neutron wall loading as low as about 1.5 MW/m², tritium breeding with nuclear heating, cooling with liquid coolant and operation temperature in the blanket, selection of structural materials with low activation, radiation shielding to achieve more that 5 order reduction at super conducting coils, configuration of high heat flux components in divertor regions, helium ash removal with the efficiency around 30%, and safety

[en] The impurity problem is one of the most important areas of study for improving Heliotron-E currentless plasmas. Impurity reduction by 2.45 GHz ECH discharge cleaning and the impurity flux in the edge region of the NBI currentless plasmas were studied by using a newly installed surface analysis station with an 'in-situ' AES system. It was confirmed that the light impurities such as C and O were well reduced by the discharge cleaning. The amount of metal impurities on the α-Si probe surface exposed to the plasma increased as the NBI power increased. The impurity level observed in one side of the probe inserted into the edge region of the NBI plasma was larger than that in the opposite side. (orig.)

[en] The effects of the plasma profile on the global energy confinement have been studied in Heliotron E with special regard to differences between heating methods (ECH, NBI and NBI + ECH). With high power NBI, peaked T_i and peaked n_e profiles (T_i(0)/(T_i) <∼ 2.7, n_e(0)/(n_e) <∼4.5) were simultaneously achieved under low recycling conditions. A peaked ne profile (n_e(0)/(n_e) >∼2.5 ) could lead to the high T_i mode where the ion heat transport in the central region is substantially reduced. By changing the ECH launching condition (on-axis, off-axis and toroidally oblique injection), the peakedness of the T_e profile could be controlled in the range 1.3 <∼ T_e(0)/(T_e) <∼ 4.5. A peaked T_e profile and a flat n_e profile (3.5 <∼ T_e(0)/(T_e), n_e(0)/(n_e) <∼ 1.8) were brought about by the well focused on-axis ECH. The ECH plasma with a peaked T_e profile has higher stored energy than that with a moderately peaked T_e profile for the same injected ECH power and the same density region. The global energy confinement time normalized by the LHD scaling, τ_E^G/τ_E^LHD, showed n_e(0)/(n_e) dependence for the low T_i mode NBI plasmas. For the high T_i mode, the n_e(0)/(n_e) dependence of τ_E^G/τ_E^LHD was weak. These findings suggest that the LHD scaling should be modified to scale the global energy confinement of the helical plasmas in a wide range of n_e(0)/(n_e). (author)

[en] A pneumatic six-pellet injector has been developed for plasma fueling applications for HELIOTRON E. The cryogenic mechanism consists of two cryogenic housings cooled by liquid helium and a pellet production disk with six holes and the shaft assembly. Frozen hydrogen pellets are formed in the disk holes. The disk is rotated from the pellet production zone to the shooting position. The pellets are propelled by high pressure hydrogen or helium gas (at pressures of up to 100 bars) from 0.52 m gun barrels. Pellet velocity and firing intervals are variable for each shot. Pellet size can be changed by replacing the pellet production disk and the gun barrels. One example of a combination of six pellet holes is three groups of two pellets, each group having a diameter of 1.2 mm, 1.5 mm or 2.0 mm and all pellets having a thickness of 1 mm. Pellet velocity ranges from 400 m/s to 1400 m/s. The time interval between each pellet firing can be changed from 0 ms to more than 100 ms. More than 90% of the pellet shots are successful in operation. One cycle presently lasts 10 minutes. Recently, a six-pellet injector has been installed on HELIOTRON E. (author). 3 refs, 7 figs, 1 tab

[en] A large superconducting helical device (Heliotron Type) has been designed for two years by Design Team (A Joint University Effort in Japan). This will be a major experimental device for the new Toki Institute (Institute for Fusion Research, Gifu Prefecture, Japan), which will be founded in 1989 by Ministery of Monbusho. The specifications of the present design option are: major radius R=4m, coil minor radius ah=1.051 m, plasma minor radius ap(plasma)=0.5-0.6 m, field period 1=2 /m=10, magnetic field B=4 T, plasma duration tm5 sec, heating power Ph=20 MW. The stored magnetic energy of this superconducting coil is greater than 2 GJ. The construction is scheduled to be completed in 1995. The results of the over all engineering study of this large super conducting helical device are presented. Necessary items of the research and development (RD) for SC coil system are also reported. (author). 3 refs.; 3 tabs

[en] This report is the first of two volumes - an executive summary and a full report - that document progress in stellarator/heliotron research in the five years (1981-1986) since a previous U.S.-EURATOM assessment of stellarator research. The present study was carried out under the terms of the IEA Implementing Agreement for Cooperation in Development of the Stellarator Concept by researchers from the Kyoto University Plasma Physics Laboratory in Japan, the Max-Planck-Institut fuer Plasmaphysik in the Federal Republic of Germany and the Oak Ridge National Laboratory and the Princeton Plasma Physics Laboratory in the United States of America. This executive summary is being published as ORNL/TM-10482 by the Oak Ridge National Laboratory, as IPP-2/286 by the Max-Planck-Institut fuer Plasmaphysik, and as PPLK-7 by the Kyoto University Plasma Physics Laboratory. The full report will be published as ORNL/TM-10483, IPP-2/287, and PPLK-8. The eight numbered sections of the executive summary correspond to the first eight chapters of the full report. An introduction to the topic is followed by an assessment of the existing data base, a discussion of the information expected from the present generation of experiments, and brief reviews of facilities needed in the future, engineering issues, and reactor considerations. The executive summary concludes with a statement of the essential ideas presented in this document and in the full report. (orig./GG)

[en] The present status of LHD (Large Helical Device) control system design is described, emphasizing on the plasma operation modes, the architecture of the LHD control system, the real-time plasma feedback system with PID or Fuzzy controllers and the construction schedule of the LHD control system. The conceptual and detailed designs are under way taking flexible and reliable operations for physics experiments into account. (author)