Non-Adiabatic Effects on Electron Beam Quality for Frequency-Tunable Gyrotrons

We propose an unconventional electron gun structure in which the emitter is located on a concave cathode surface with a non-uniform electric field. Such a design violates the intuition that an emitter should place close to a uniform electric field to reduce the velocity spread. The commonly employed design guide based on the adiabatic condition predicts a huge velocity spread of 24%, but the simulation using EGUN code and verified with CST particle studio shows a very low spread of 2.8%. Examining the magnetic moment and the kinetic energy of the beam reveals that the electrons experience a relatively long acceleration process due to the much weak electric field. That's why the non-adiabatic effect matters. In addition to the cyclotron compression and the E$\times$B drift, the "resonant" polarization drift plays a crucial role in reducing the overall velocity spread.Simulations show a decent beam quality with the pitch factor of 1.5 and the transverse velocity spread of 2.8% over a wide range of the magnetic field (7.4-8.0 T) and the beam voltage (12-22 kV) with a high structural tolerance. The promising results with the wide working range enable the development of continuous frequency-tunable gyrotrons.Comment: 5 pages, 5 figures, and 2 table

formation of a laminar electron flow for 300GHz high-power pulsed gyrotron

This paper describes the design of a triode magnetron injection gun for use in a 200 kW, 300 GHz gyrotron. As power and frequency increase, the performance of the gyrotron becomes quite sensitive to the quality of the electron beam. Formation of a laminar electron flow is essential for the realization of a high quality beam with a small velocity spread. In this study, a new method is developed for a quantitative evaluation of the laminarity and is applied to optimize the electrode design. The laminarity depends not only on conventional design parameters such as the cathode slant angle but also on the spatial distribution of the electric field along the beam trajectory. In the optimized design, the velocity pitch factors, a, larger than 1.2 are obtained at 65 kV, 10A with spreads, Da, less than 5%

Observation of Dynamic Interactions between Fundamental and Second-Harmonic Modes in a High-Power Sub-Terahertz Gyrotron Operating in Regimes of Soft and Hard Self-Excitation

Dynamic mode interaction between fundamental and second-harmonic modes has been observed in high-power sub-terahertz gyrotrons [T. Notake et al., Phys. Rev. Lett. 103, 225002 (2009); T. Saito et al. Phys. Plasmas 19, 063106 (2012)]. Interaction takes place between a parasitic fundamental or firstharmonic (FH) mode and an operating second-harmonic (SH) mode, as well as among SH modes. In particular, nonlinear excitation of the parasitic FH mode in the hard self-excitation regime with assistance of a SH mode in the soft self-excitation regime was clearly observed. Moreover, both cases of stable twomode oscillation and oscillation of the FH mode only were observed. These observations and theoretical analyses of the dynamic behavior of the mode interaction verify the nonlinear hard self-excitation of the FH mode

鹿児島県における退院後生活環境相談員の業務の現状と課題 : 精神保健福祉士へのアンケート調査から明らかになったこと

The purpose of this study was to clarify the current status and issues of “social worker for living conditions after discharge” that was introduced in 2014 by the Ministry of Health, Labor and Welfare in Kagoshima. Of the 51 psychiatric hospitals in Kagoshima, the survey aimed at examining the viewpoints of social workers for living conditions after discharge in 38 hospitals regarding the living conditions of patients after being discharged. The social workers for living conditions after discharge were members of Kagoshima Association of Psychiatric Social Workers, which is a cooperative research organization.The results of the survey revealed that 58 social workers for living conditions after discharge (45.3%) experienced difficulty and / or conflict but had also experienced a sense of fulfillment and accomplishment. In addition, 28 categories were extracted from the data of 3 open-ended questions. The results thus revealed the problems related to completion of an inpatient care plan within the prescribed deadline; conflicts that the social workers experienced due to the living conditions after the patients have been discharged and the institution’s understanding regarding the same; varying degrees of recognition of varied occupations enjoyed at conferences; the condition of powerless people; the difficulties of coordinating chronic shortages, especially when the person and his/her family had different intentions; and high ratio of office work and insufficient direct support

Exploring Biomolecular Self-Assembly with Far-Infrared Radiation

Physical engineering technology using far-infrared radiation has been gathering attention in chemical, biological, and material research fields. In particular, the high-power radiation at the terahertz region can give remarkable effects on biological materials distinct from a simple thermal treatment. Self-assembly of biological molecules such as amyloid proteins and cellulose fiber plays various roles in medical and biomaterials fields. A common characteristic of those biomolecular aggregates is a sheet-like fibrous structure that is rigid and insoluble in water, and it is often hard to manipulate the stacking conformation without heating, organic solvents, or chemical reagents. We discovered that those fibrous formats can be conformationally regulated by means of intense far-infrared radiations from a free-electron laser and gyrotron. In this review, we would like to show the latest and the past studies on the effects of far-infrared radiation on the fibrous biomaterials and to suggest the potential use of the far-infrared radiation for regulation of the biomolecular self-assembly