著者

Andrey V. ARZHANNIKOV Sergey V. BEDENKO Aleksandr A. IVANOV Dmitry G. MODESTOV Vadim V. PRIKHODKO Stanislav L. SINITSKY Igor V. SHAMANIN Vladimir M. SHMAKOV

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.14, pp.2402101, 2019-06-03 (Released:2019-06-15)

参考文献数

7

被引用文献数

1

---

Results of computer simulation of the fuel evolution in thorium nuclear cycle in a subcritical assembly in case of thorium-plutonium initial composition is presented in the paper. The simulation is conducted for specialized facility in which a long solenoid with hot plasma is situated inside of the subcritical fuel assembly. The plasma column produces additional neutrons due to D-D fusion reaction that are necessary for a fission reactor with this assembly. Total intensity of neutron emission over all plasma volume with the length of 3 m is N = 2 × 1016 neutrons per second. We have chosen the percentage of plutonium 5% in thorium-plutonium initial composition and in this case, the effective coefficient of neutron multiplication is 0.95, as shown by our simulation. The fuel evolution was calculated for duration of operation time 3000 days. As a result, we have demonstrated the decrease in the coefficient of neutron multiplication and in the power of the nuclear fission process in the described time. Results of simulations are discussed.

著者

塚本 俊介 前田 貴昭 池田 元吉 秋山 秀典

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

プラズマ・核融合学会誌 = Journal of plasma and fusion research (ISSN:09187928)

巻号頁・発行日

vol.79, no.1, pp.39-42, 2003-01-25

被引用文献数

7 7

---

Pulsed high voltage was applied to logs used for mushroom culturing to mushroom growth. An experiment was carried out in an attempt to increase shiitake mushroom yield. Results showed that the weight of shiitake mushroom yield was double that of a normal group cropped in a month. Another experiment was performed to estimate the effect of electrical stimulation on the growth of hyphae. Results of that experiment showed a slight influence on the growth of hyphae, and showed some possibilities this method can improve mushroom culturing techniques.

著者

Ryoji HIWATARI Youji SOMEYA Hiroyasu UTOH Yoshiteru SAKAMOTO

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.18, pp.1205077, 2023-08-28 (Released:2023-09-06)

参考文献数

9

---

This article presents the concept of unlimited fusion-energy station (U-FESTA), comprising a fusion power plant and a lithium (Li) recovery facility to recover Li from seawater, for example the Li-separation method by ionic conductor (LiSMIC). To realize the U-FESTA, we discuss the relationship among the seawater-based Li-recovery efficiency, blanket technology on 6Li enrichment, intake cooling seawater in a power plant, and the blanket-replacement period.

著者

Hiroshi GOTA Samuel ANDREASON George VOTROUBEK Chris PIHL John SLOUGH

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.2, pp.S1050, 2007 (Released:2008-02-26)

参考文献数

5

---

The high flux source for the Pulsed High Density Experiment (PHDX) has been constructed, and field-reversed configuration (FRC) plasmas are being produced. To diagnose FRC plasma temperatures three kinds of diagnostic systems have been set up on PHDX; λ = 632.8 nm He-Ne laser interferometer system at the midplane for total temperature Ttotal, 16 channel spectrometer for ion temperature Ti and soft x-ray (SXR) measurement system for electron temperature Te viewed along z-axis, respectively. The SXR measurement system consists of five sets of collimators and AXUV100 photodiodes with directly deposited filters which have different bandpass regions. As a result of preliminary temperature diagnostics, the following plasma parameters are estimated during a relatively quiescent phase of FRCs; Ttotal ∼ 50 eV, Ti ∼ 50 eV and Te ∼ 25 eV. This result does not agree with the equilibrium relation of Ttotal ≈ Ti + Te, and it must be caused by plasma condition and our assumptions in the spectral analysis.

著者

Yuya KAWAMATA Akira EJIRI Kyohei MATSUZAKI Yuichi TAKASE Naoto TSUJII Takumi ONCHI Yoshihiko NAGASHIMA

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.14, pp.1402072, 2019-04-11 (Released:2019-05-22)

参考文献数

9

被引用文献数

2

---

The stray light is a major problem in Thomson scattering (TS) measurements. The main cause of stray light is unnecessary divergence of the incident laser beam and an aperture is a standard component to reduce it. In order to improve the aperture configuration (including size, number and position in the laser injection tube), a peripheral beam profile monitor, consisting of a screen with a through hole for the laser beam and a CMOS camera, was developed. Instead of the actual laser injection tube a mock-up tube was used to measure the peripheral beam profiles under various aperture configurations. The configuration with four 15mm diameter apertures was chosen and installed on the TS system for the TST-2 spherical tokamak. The stray light was reduced to about 4% compared to the smaller diameter injection tube with no apertures. As a result, it became possible to make TS measurements in the electron density range above 1.0 × 1017 m−3.

著者

Shintaro KOIKE Toshiki TAKAHASHI Naoki MIZUGUCHI Osamu MITARAI

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.13, pp.1203008, 2018-02-09 (Released:2018-03-05)

参考文献数

12

---

Three-dimensional resistive MHD simulation was carried out in order to develop a method to fuel the plasma core by merging two Spherical Torus (ST) plasmas. A relatively small ST plasma was translated into the axial direction by external magnetic field control and made to collide with the larger ST. In this calculation, ballooning instability occurred in both plasmas during translation, while the magnetic surface was observed to collapse from the Poincare plot of the magnetic lines. It was observed that the magnetic lines in the core regions of the two STs were connected to each other and that the merging was completed.

著者

Akinobu MATSUYAMA Ryuichi SAKAMOTO

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.17, pp.2402017, 2022-03-30 (Released:2022-04-23)

参考文献数

10

被引用文献数

1

---

Cryogenic neon pellets of 3 mm in diameter were injected into neutral beam injection (NBI) heated discharges on the Large Helical Device (LHD). The time response of far infrared (FIR) interferometer has pointed out a relatively slow assimilation of the ablated materials compared to the cases of hydrogen injection. This is consistent with the neutral gas and plasma shielding (NGPS) model prediction, showing that strong line emission inside the ablation cloud limits the cloud temperature and the expansion velocity along the magnetic field line. Measured penetration depths were also compared, being well reproduced by the code prediction when the contribution from 180 keV fast ions produced by tangential NBI is taken into account.

著者

Takumi KODAHARA Makoto SASAKI Yuichi KAWACHI Yuki JAJIMA Tatsuya KOBAYASHI Takuma YAMADA Hiroyuki ARAKAWA Akihide FUJISAWA

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.18, pp.1202036, 2023-06-05 (Released:2023-06-07)

参考文献数

9

被引用文献数

1

---

Multi-field singular value decompositions (SVDs) is applied to turbulence obtained in a cylindrical magnetized plasma, PANTA. This method enables us to obtain the spatial mode structures with common temporal evolution of different physical quantities, such as the fluctuations of density and flows. Turbulence driven particle transport is evaluated by the method. It is shown that only the coupling of the same mode drives the transport, which stems from the orthogonality of the SVD. Thanks to this characteristics, the number of degrees of freedom which plays roles for the transport dynamics could be significantly reduced.

著者

Satoru YAJIMA Yuichi TAKASE Akira EJIRI Naoto TSUJII Hibiki YAMAZAKI Charles P. MOELLER Takahiro SHINYA Yuki TAKEI Yoshiyuki TAJIRI Yusuke YOSHIDA Akito SATO Akichika KITAYAMA Naoki MATSUMOTO

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.13, pp.3402114, 2018-09-25 (Released:2018-10-17)

参考文献数

9

被引用文献数

3 9

---

In the TST-2 spherical tokamak device, we carried out a fully non-inductive current startup experiment by Landau damping of the Lower Hybrid Wave (LHW). Capacitively Coupled Combline Antennas (CCCAs) were used for wave injection. The antennas are located on the outboard side and the top side of the vacuum vessel, and by reversing the toroidal magnetic field, it is possible to simulate the case of wave injection from the bottom side. The highest plasma current of 26.7 kA was achieved by top injection with the reversed toroidal magnetic field. According to numerical calculation using ray tracing and Fokker-Planck codes (GENRAY/CQL3D), the downshift of the parallel wavenumber helped the tail of the electron velocity distribution extend to higher energy than the other cases. Additionally, in order to evaluate the directionality of the wavenumber spectrum which is also important for efficient current drive, a finite element solver (COMSOL) was used. In order to avoid deterioration of the wavenumber spectrum, one limiter of the outboard antenna should be moved away toroidally by 70 mm from the current position, and the preferred distance between the antenna and the cutoff density layer is about 2 cm.

著者

Yongtae KO Naoto TSUJII Yuichi TAKASE Akira EJIRI Osamu WATANABE Hibiki YAMAZAKI Kotaro IWASAKI Peng YI James H.P. RICE Yuki OSAWA Takuma WAKATSUKI Maiko YOSHIDA Hajime URANO

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.16, pp.1402056, 2021-04-21 (Released:2021-05-12)

参考文献数

20

被引用文献数

5

---

We investigated electron cyclotron (EC) wave assisted low voltage Ohmic start-up in the conventional field null configuration (FNC) and the trapped-particle configuration (TPC) in the TST-2 spherical tokamak device. The upper pressure limit for successful burn-through increased when EC power was applied for both the FNC and TPC. On the other hand, at low prefill pressure, breakdown was delayed in the FNC start-up. The achievable plasma current also decreased especially at high EC power. By applying the TPC, fast breakdown was recovered even at high EC power. The plasma current ramp-up rate was also greater with TPC compared with FNC at the same loop voltage waveform. The lower prefill pressure limit for successful breakdown expanded in the TPC compared to that in the FNC. The higher vertical field decay index resulted in faster EC breakdown. The reduction of the upper pressure limit due to impurities was the same in the FNC and TPC indicating that the poloidal field configuration did not significantly affect the upper pressure limit for successful burn-through.

著者

James H.P. RICE Naoto TSUJII Yuichi TAKASE Akira EJIRI Osamu WATANABE Hibiki YAMAZAKI Yi PENG Kotaro IWASAKI Yuki AOI Yongtae KO Kyohei MATSUZAKI Yuki OSAWA

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.15, pp.2402009, 2020-04-06 (Released:2020-05-08)

参考文献数

13

被引用文献数

4

---

A new Langmuir probe has been designed and installed in TST-2 for measurements of Scrape-Off Layer plasmas (SOL). Non-inductive current drive is considered essential for spherical tokamak reactors. It has previously been shown that a large amount of injected Lower Hybrid Wave (LHW) power is lost in the SOL [1]. A full density profile of SOL conditions is necessary to accurately simulate the propagation of LHW in TST-2. A new probe was designed for durability, larger signal and Mach probe measurements. The new probe has been installed in TST-2 and results have been obtained. Temperature measurements show Te = 30 - 50 eV during RF injection and <10 eV otherwise. Density measurements show ne = 2.0 × 1015 m−3 and 1.5 × 1016 m−3 during flat-top RF power injection from Outboard- and Top-launch antennas, respectively. This is above the cut-off density for the 200 MHz LHW (5 × 1014 m−3) in TST-2, thus LHW can propagate through SOL plasma.

著者

Naoto TSUJII Yusuke YOSHIDA Yuichi TAKASE Akira EJIRI Osamu WATANABE Hibiki YAMAZAKI Yi PENG Kotaro IWASAKI Yuki AOI Yongtae KO Kyohei MATSUZAKI James H.P. RICE Yuki OSAWA

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.15, pp.2402010, 2020-04-06 (Released:2020-05-08)

参考文献数

13

被引用文献数

2 4

---

Removal of the central solenoid is considered essential to realize a spherical tokamak fusion reactor, but non-inductive plasma start-up is a challenge. Start-up using lower-hybrid (LH) waves has been studied on the TST-2 spherical tokamak at the University of Tokyo. The equilibrium poloidal field is believed to be generated mostly by the wave driven fast electrons, which are highly non-thermal and have large orbit excursions from the flux surfaces due to low plasma current. Such an equilibrium can be qualitatively different from the Grad-Shafranov equilibrium routinely used for internal magnetic field reconstruction in a tokamak. In this work, the effect of fast electrons on the MHD equilibrium was investigated by considering the equilibrium solution of the hybrid-MHD model [Y. Todo and A. Bierwage, Plasma Fusion Res. 9, 3403068]. The fast electron distribution function was estimated using a LH current drive simulation based on ray-tracing and an orbit-averaged Fokker-Planck solver. The equilibrium solution of the hybrid-MHD model was successfully fitted to the magnetic and kinetic measurements. The resulting poloidal flux function was more skewed towards the outboard side when fast electrons were introduced, which was more consistent with the density profile measured by the Thomson scattering diagnostic.

著者

Tsuyoshi YAMAMOTO Eiichi YATSUKA Takaki HATAE Kazuya OTA Yasunori HASHIMOTO Kitaru NAKAMURA Tatsuo SUGIE Masaki TAKEUCHI Sin-iti KITAZAWA Hiroaki OGAWA Yasunori KAWANO Kiyoshi ITAMI

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.11, pp.2405114, 2016-10-05 (Released:2017-03-01)

参考文献数

15

---

There is a need to develop ITER instrumentation and control (I&C) systems with high reliabilities. Interlock systems that activate machine protection functions are implemented on robust wired-logic systems such as programmable logic controllers (PLCs). We herein propose a software tool that generates program code templates for the control systems using PLC logic. This tool decreases careless mistakes by developers and increases reliability of the program codes. A large-scale engineering database has been implemented in the ITER project. To derive useful information from this database, we propose adding semantic data to it using the Resource Description Framework format. In our novel proposal for the ITER diagnostic control system, a guide words generator that analyzes the engineering data by inference is applied to the hazard and operability study. We validated the methods proposed in this paper by applying them to the preliminary design for the I&C system of the ITER edge Thomson scattering system.

著者

Fujio MAEKAWA Transmutation Experimental Facility Design Team

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.13, pp.2505045, 2018-05-10 (Released:2018-07-14)

参考文献数

11

被引用文献数

2 3

---

The partitioning and transmutation (P-T) technology have promising potential for volume reduction and mitigation of degree of harmfulness of high-level radioactive waste. JAEA is promoting the development of the P-T technology by using an accelerator-driven system (ADS). To facilitate the development, JAEA has a plan to construct Transmutation Experimental Facility (TEF) as one of the experimental facilities of Japan Proton Accelerator Research Complex (J-PARC). TEF consists of two individual facilities: ADS Target Test Facility (TEF-T) and Transmutation Physics Experimental Facility (TEF-P). TEF-T equips with a liquid lead-bismuth spallation target bombarded by a 400 MeV - 250 kW proton beam in which candidate proton beam window materials of the ADS are to be irradiated. TEF-P equips with a critical/subcritical assembly to investigate physical and dynamic properties of the accelerator-driven system by using a low power (10 W) proton beam. Nuclear fuels containing minor actinide are to be loaded to the assembly. Comprehensive R&D activities to support the TEF construction have been conducted, and a technical design report of TEF-T was issued in March 2017.

著者

Kei TAKAKURA Takayuki SAKO Haruo MIYADERA Kenichi YOSHIOKA Yoshiji KARINO Kohichi NAKAYAMA Tsukasa SUGITA Daisuke UEMATSU Kohei OKUTOMO Jun HASEGAWA Toshiyuki KOHNO Eiki HOTTA

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.13, pp.2406075, 2018-06-12 (Released:2018-08-22)

参考文献数

9

被引用文献数

5

---

Feasibility studies on neutron radiography using an inertial electrostatic confinement (IEC) neutron source were carried out. A Monte Carlo analysis was carried out to evaluate the feasibility of neutron radiography experiment. Imaging tests using a medium-sized IEC neutron source were conducted with the indirect method using a dysprosium (Dy) foil and an imaging plate. Neutron images of objects consisting of six Cd pins and an array of B4C powder contained in a stainless-steel blade were obtained. The numerical and experimental results confirmed that the IEC neutron source can be applied to neutron radiography even with relatively low neutron flux of ∼102 n/s/cm2.

著者

Moe AKIMITSU Yasushi ONO Qinghong CAO Hiroshi TANABE

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.13, pp.1202108, 2018-09-25 (Released:2018-10-17)

参考文献数

6

被引用文献数

1 3

---

2D high-resolution magnetic probe arrays for local 2D magnetic field measurements of magnetic reconnection have been developed using advanced printed-circuit board (PCB) technology. Each of these arrays can be equipped with all three components of magnetic pickup coils (5 × 3 mm2). Each coil is composed of a two-sided coil circuit pattern with a line width of 0.05 mm. Based on this new probe technique, we conducted high-resolution and high-accuracy measurements of the current sheet to determine the formation and ejection of plasmoid in a current sheet of two merging tokamak plasmas for the first time.

著者

Masaharu MATSUMOTO Hideyuki USUI Masanori NUNAMI Masao NAKAMURA Iku SHINOHARA

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.8, pp.2406132, 2013-09-26 (Released:2015-06-13)

参考文献数

9

被引用文献数

2 3

---

A parallelized two-dimensional full particle-in-cell (PIC) simulations with an adaptive mesh refinement (AMR) technique for the interaction of solar wind with kinetic scale magnetosphere around a magnetic sail are conducted. For multi-scale simulations, the newly developed AMR-PIC code has a method to modify the grid size and time step interval of computational domain in the midst of the simulations temporally and locally. In the simulation results under the typical working condition introducing the AMR technique, it is shown that the direction of interplanetary magnetic field depend strongly on the magnetospheric configuration including electron dynamics and Alfven bow shock structure. Although more validation studies are needed, the AMR-PIC code shows the worth of development for multi-scale simulations.

著者

Ryuichi SAKAMOTO Suguru MASUZAKI Junichi MIYAZAWA LHD Experimental Group

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.1, pp.019, 2006 (Released:2006-07-27)

参考文献数

4

被引用文献数

4 6

---

A high-luminosity striation, which rotates within a flux surface of the plasma boundary having helical structure, has been observed in the LHD plasmas by means of a fast camera. The striation appears when the plasma is shrinking due to excessive gas fueling despite the existence of neutral beam heating.

著者

Hitoki YONEDA Shigeaki NISHIO

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.12, pp.1301046, 2017-11-28 (Released:2017-12-21)

参考文献数

6

---

Detailed study of electrons in warm dense matter is a key to understanding material properties. Up to now there are many methods to detect electron spectral features with optical lasers and x-rays. Here we propose and demonstrate a new measurement method using inelastic Compton scattering of hard x-ray probe radiation. By using a high energy photon beam, above 100 keV, the change of the electron momentum distribution is observed through a change of the scattered x-ray spectrum even in a solid density plasmas.

著者

Yasunobu ARIKAWA Yusuke KATO Yuki ABE Shuto MATSUBARA Hidetaka KISHIMOTO Nozomi NAKAJIMA Alessio MORACE Akifumi YOGO Hiroaki NISHIMURA Mitsuo NAKAI Shinsuke FUJIOKA Hiroshi AZECHI Kunioki MIMA Shunsuke INOUE Yoshihide NAKAMIYA Kensuke TERAMOTO Masaki HASHIDA Shuji SAKABE

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.13, pp.2404009, 2018-02-15 (Released:2018-03-27)

参考文献数

18

被引用文献数

3

---

A short and high-intensity neutron pulse can be produced efficiently by using photonuclear reactions caused by Bremsstrahlung hard X-rays in a lase-irradiated high-Z target. The efficient and repetitive neutron generation was demonstrated with the combination of 1 Hz, 0.5 J, 25 fs, 5 × 1019 W/cm2 laser pulses and a rotating tungsten disc targe. Here we applied double laser pulse irradiation scheme to increase the neutron generation efficiency. The first low-intensity laser pulse produces a long-scale under-critical-density plasma on the tungsten target surface prior to the second pulse irradiatio. High energy electrons above the ponderomotive scaling value are accelerated by the second hig-intensity pulse in the preformed plasm, this results in the increment of hard X-ray photons and photonuclear neutron. 3.5 × 104 neutron/pulse was obtained with optimized laser irradiation conditions.