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An electromagnetic surface wave carrying orbital angular momentum (AM) is called plasmonic vortex that also carries spin AM originating from evanescent field. In this study, spin and orbital AM of plasmonic vortex in a terahertz cylindrical corrugated waveguide (CCW) are analyzed. We report the extrinsic spin AM of the plasmonic vortex for the first time. The extrinsic spin AM is produced by the rotation of the polarization of the plasmonic vortex whose rotation axis is positioned at the vicinity of the CCW wall. The extrinsic spin AM depends on the intrinsic orbital AM and radius of CCW. The plasmonic vortex with sufficiently large orbital AM carries large spin AM per photon. This large extrinsic spin AM expands degree of freedom of the spin AM and would be applied to various terahertz technologies., Comment: 5 pages, 4 figures

We study a disk cathode in the weakly relativistic region less than 100 kV by comparing the conventional tubular cathode. The disk cathode is an explosive electron emission cathode made of bare metal. The beam generated by the disk cathode has the more uniform distribution and has the higher current density compared with the tubular cathode with velvet. For the uniform emission, some surface roughness of 1 ����m order is required on the emission surface. Metals such as aluminum, copper and stainless steel are tested as the cathode. Up to now, the best result is obtained by a copper cathode. In view of application to the weakly relativistic oversized backward wave oscillator, the disk cathode is superior to the tubular cathode and is effective for the high-power operation.

An electric brake by a three-phase short-circuit system used as the brake equipment of a small wind turbine damages the rotor blades by a rapid revolution stopping of the generator. Moreover, the generators windings may also be damaged by a large short-circuit current. In this paper, the electric braking circuit using the NTC thermistors (negative temperature coefficient resistors) is proposed as a braking system for a cheaper and safe stop of the small wind turbine. The effect under the natural wind condition is examined by the field test using a 500W small wind turbine.

The Cherenkov instability used in slow-wave devices has been well studied in the literature. However, in previous analyses, the beam motion is restricted to the longitudinal direction assuming an infinitely strong magnetic field. For the finite strength magnetic field, the transverse beam perturbation cannot be ignored and leads to the slow cyclotron instability. Recently, a new version of self-consistent field theory considering three-dimensional perturbation has been developed based on a solid beam, in which the effect of the transverse perturbation appears as a surface charge at a fixed boundary. In the case of a thin annular beam, the boundary is modulated and is essentially different from the solid beam case. We propose a self-consistent field theory considering the moving modified boundary surface. The slow cyclotron instability due to the modulation of an infinitesimally thin annular electron beam is presented.

Backward wave oscillators (BWOs) have been studied as a candidate high-power microwave source. To increase the operation frequency, an oversized slow-wave structure (SWS) is used. The operation at reduced voltage is preferable for practical applications. This work is aimed at numerically examining the operation mode of a weakly relativistic oversized BWO. We examine not only the axisymmetric transverse magnetic mode but also the non-axisymmetric hybrid modes of the oversized SWS. Both of them are candidates for the operation modes. These modes are surface waves whose fields are concentrated near the SWS wall. They overlap in frequency and are not separated by stop-bands. For an efficient beam interaction, the injected electron beam needs to be controlledmore accurately\nthan in the non-oversized SWS case.

Oscillation starting condition of a K-band oversized backward wave oscillator (BWO) is investigated experimentally. Periodically corrugated slow-wave structure (SWS) is used, which is designed for K-band operation in a weakly relativistic region, i.e. 30-80 kV. The beam current is in the range of 50- 00 A. It is shown experimentally that there exists a critical beam energy (starting energy) for the meaningful radiation. The starting energy is more critical than the starting current in the oversized BWO. It decreases by increasing the SWS length. Above the starting energy, the output owers up to about 100 kW are obtained. The typical frequency observed is about 23 GHz. Nonaxisymmetric hybrid HE11 mode as well as axisymmetric TM01 mode is observed. The operation mode is able to be controlled by the SWS length and the magnetic field strength.

The previous studies of backward wave oscillators (BWOs) have been restricted in the operation at the fundamental axisymmetric TM mode. owever, nonaxisymmetric operations of BWO are observed in the experiments and become important. In this work, the Rayleigh-Bessel (R-B) method is improved in order to analyze the nonaxisymmetric as well as axisymmetric fields in a periodic slow-wave structure (SWS). This method is based on the Rayleigh hypothesis, whose limit has been argued extensively. For the X-band SWS, the modulation depth is about 4 times of the theoretically established limit of the Rayleigh hypothesis. We compare the R-B method with another one based on a numerical integration of Maxwell equations, which is free from the Rayleigh hypothesis. The field properties derived by the R-B method show some singularities inside the corrugation due to the Rayleigh hypothesis. However, regardless the singularities, the dispersion characteristics and the fields outside the corrugation are in very good agreement with those by the numerical integration. The validity of the R-B method is discussed.

Normal mode and their high-frequency instabilities are analyzed self-consistently considering electron beams propagating along a magnetic field in unbounded and bounded systems. For unbounded dielectric system, the beam couples with electromagnetic waves corresponding to X and O modes, resulting in the slow cyclotron and Cherenkov instabilities, respectively. For cylindrically bounded system, a self-consistent field theory is developed. Axisymmetric and nonaxisymmetric normal modes obtained are hybrid modes. Cherenkov instability for the EH mode and slow cyclotron instability for EH and HE modes are confirmed in a cylindrical slow wave structure system.

A large diameter backward wave oscillator (BWO) without guiding magnetic field is demonstrated experimentally. The beam propagation is achieved by filling SWS with helium gas. The oscillation mode of the BWO might be the axisymmetric TM mode as well as TE mode. The output power of the TM mode is less than lkW, which corresponds to electronic efficiency less than 0.004 %. At zeo-magnetic field, the conventional Cherenkov and cyclotron interactions are degenerate and perturbed beam motions perpendicular as well as parallel to an axial direction should be taken into account. In the degenerate beam interaction, surface charge σ1 at beam-vacuum boundary plap essential role. Numerical analysis shows that the degenerate interaction is superior to the conventional Cherenkov interaction in the high current region above 100 A and in the weakly relativistic energy region., 本報告書は、大学共同利用機関法人自然科学研究機構核融合科学研究所からリポジトリ登録許諾を得て、平成9年度～平成11年度科学研究費補助金(基盤研究(C)(2))研究成果報告書(課題番号:09680456)「チェレンコフ・サイクロトロン縮重相互作用によるマイクロ波発生の研究」（小椋一夫著）から複製したものである。

Studies of slow cyclotron maser operation of a slow-wave device are presented. The beam voltage is weakly relativistic, less than 100 kV. The slow-wave structure is a periodically corrugated oversized waveguide for K-band operation. When using rectangular corrugation having a relatively small ratio of corrugation width to periodic length of about 20 %, the dispersion curve near the upper cut-off becomes flat and second harmonic slow cyclotron maser operation is observed in the low-energy region near 30 kV. Another type of combined resonance of Cherenkov and slow cyclotron interaction is also demonstrated in which an absolute instability is driven by the slow cyclotron interaction. By using sinusoidal corrugation and rectangular corrugation having a 50 % ratio of corrugation width to periodic length, amplification effects due to the fundamental and second harmonic slow cyclotron interactions are observed.

Three kinds of models are used for beam instability analyses: those based on a solid beam, an infinitesimally thin annular beam, and a finitely thick annular beam. In high-power experiments, the electron beam is an annulus of finite thickness. In this paper, a numerical code for a sinusoidally corrugated waveguide with a finitely thick annular beam is presented and compared with other models. Our analysis is based on a new version of the self-consistent linear theory that takes into account three-dimensional beam perturbations. Slow-wave instabilities in a K-band oversized sinusoidally corrugated waveguide are analyzed. The dependence of the Cherenkov and slow cyclotron instabilities on the annular thickness and guiding magnetic field are examined.

Studies on slow-wave devices with a novel disk cathode and two types of rectangular corrugation are reported. The beam voltage is weakly relativistic, which is less than 100 kV. A disk cathode can generate a uniformly distributed annular beam in the weakly relative region. Rectangular corrugation having the ratio of the corrugation width to the periodic length of 50 or 20% is used. Using the former, output powers of about 200kW are obtained at around 100 kV. For the latter, the effect of slow cyclotron resonance is observed in the low-energy region of around 30 kV. Output powers of slow cyclotron masers are in the range of a few hundred W. The operation mode of a slow cyclotron maser can be controlled between axisymmetric and nonaxisymmetric modes by changing the end condition of rectangular corrugation.

The cherenkov and slow cyclotron instabilities driven by an axially injected electron beam in a cylindrical waveguide are studied using a new version of the self-consistent linear theory considering three-dimensional beam perturbations. There are three kinds of models for beam instability analysis, which are based on a cylindrical solid beam, an infinitesimally thin annular beam, and a finitely thick annular beam. Among these models, the beam shape properly representing the often used actual annular electron beams is the finitely thick annulus. We develop a numerical code for a cylindrical waveguide with a finitely thick annular beam. Our theory is valid for any beam velocity. We present eigen-modes of the cylindrical system with the plasma and beam. Instabilities driven by the annular beam in a dielectric-loaded waveguide are also examined.

We report an oversized K-band backward wave oscillator (BWO) operating above 20 GHz in the weakly relativistic region less than 100 kV. It is very important to prevent microwave from going into the beam diode, since intense microwaves will harmfully affect beam generation. A weakly relativistic oversized BWO is demonstrated using a Bragg reflector at the input end of slow wave structure (SWS). The effect of the Bragg reflector on the BWO operation is examined, by changing the boundary condition at the SWS input end. The Bragg reflector improves the performance of the oversized BWO.

I had the opportunity to participate in the five major negotiations between China and Japan from 1972 to 1975 (i.e., the talks over the normalization of diplomatic relations, and the aviation, trade, shipping and fishery agreements), and to observe the tactics, both offensive and defensive, used by the Chinese participants. Personal impressions are bound to be biased, but fortunately there are at least two books which give us detailed accounts of negotiations between China and Japan in the post-war period. These are The Record of Fishery Talks between China and Japan and The Secret Memorandum of Sino-Japanese Negotiations. The former, written and edited by the Japan-China Fishery Association, whose leaders negotiated with China in 1955, is a complete record of the first fishery talks between the Japanese fishermen's organization and Chinese authorities. These negotiations centred on the regulations which Japanese and Chinese fishermen were to observe in the East China and Yellow Seas in order to avoid collisions and other accidents. The negotiations also covered some conservation measures, such as the establishment of several conservation zones along the coast of China and seasonal restrictions of the catch of some types of fish.

application/pdf, The present experiments were performed to study the effect of floral preservative Kagawa solution (KS) and storage conditions on the vase life and quality of the cut flowers of Lilium longiflorum THUNB. Cv., "Georgia". The following results were obtained. (1) Vase life of the cut lily was greatly affected by the storage temperature. Temperature effective for keeping quality of the cut flowers was 0 and 5℃ ; 10℃ was not recommendable. (2) The use of KS immediately after the harvest was effective to prolong the vase life and normal elongation of flower buds. (3) Growth of tight flower buds was disturbed by dry storage and the flowers were inferior in quality as compared to those grown under the normal condition., テッポウユリ"ジョージア"を材料として, 花の発達段階が5つの切花について切花保存液Kagawa solution (KS) の効果と, あわせて貯蔵方法について検討した結果, 以下のことが明らかとなった. (1) 貯蔵後の切花の日持は貯蔵温度に大きく左右され, 0,5℃は効果的であるが10℃は劣った. (2) 採花後KSに連続して挿すと, 日持は長くなり, つぼみも大きくなった. (3) 乾燥状態で貯蔵すると, つぼみの生長が妨げられ, 開いた花は見劣のする小さい花であった.

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