Yuki Kawasumi

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The wireless LAN technology known as WiFi (or wireless fidelity) which is the standard developed by the IEEE 802 Committee is now introduced by internet service providers or by the network operators in the metropolitan hectic areas of developed countries at so-called hotspots such as airports, hotels, cafes, railway stations, etc and facilitates to provide(More)
The fast potential change near the separatrix is measured directly at the L-H transition by a heavy-ion-beam probe. The potential changes with two different time scales at the L-H transition triggered by a sawtooth crash: it drops at first with the time scale of 10--100 mus just after the arrival of the heat pulse due to the sawtooth crash. Then, it(More)
When Ohmically heated low-density plasmas are additionally heated by higher-harmonics ion-cyclotron-range-of frequency heating, heated by neutral beam injection, or strongly gas puffed, the intensity of zonal flows in the geodesic acoustic mode frequency range in the tokamak core plasma decreases sharply and that of low-frequency zonal flow grows(More)
The concentrations of phosphorus determined by spectrophotometric analysis (soluble reactive phosphorus; SRP) and ion chromatography (orthophosphate only) were compared in fresh water from inflowing rivers of Lake Biwa (Shiga, Japan) and its outflow (Seta River). The high-volume sample injection and high-capacity analytical column used for ion(More)
The confinement of ohmically heated stellarator plasma is studied experimentally. The energy confinement time ¿E increases with the total rotational transform angle ¿¿ in the case of ¿¿/2¿ < 0.25, that is, q¿(a) > 4, while ¿E decreases with ¿¿/2¿ > 0.3, that is, q¿(a) < 3-4, which is consistent with the Alcator scaling. When the rotational transform angle(More)
It is shown that the low-density Ohmically heated tokamak plasmas have streamerlike eddies at the outer region at normalized minor radius of about 0.7 and high-frequency zonal flows of large amplitudes in the core. The amplitudes of the eddies ePhi/kT(e) and n(e)/n(e) are of order of 0.5, similar to that of blobs in the tokamak plasma boundary. The(More)
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