In the axisymmetrized tandem mirror GAMMA 10, thermal-barrier and plug potentials have been formed in the axisymmetric mirror cells at both ends and directly measured with Au neutralbeam probes and end-loss analyzers. Strong end-loss reduction associated with the potential formation results in enhancement of the axial particle confinement time 100 times over the mirror confinement time without plugging, in reasonable agreement with Pastukhov formula. An empirical scaling on nonambipolar radial ion confinement time in the axisymmetrized field configuration is presented.PACS numbers: 52.55.Jd Current tandem mirror researches focus on improvement of confinement properties over the original configuration.

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Alfven ion-cyclotron modes are generated over a wide range of anisotropy parameter P±(T±/T\\) 2 in ICRF-heated central cell plasmas of the GAMMA 10 tandem mirror. The fluctuations are observed at a small driving force in the convectively unstable region predicted theoretically in an infinite plasma. Before reching the ft limit of p± = 3.52x (T\\/T±) 2 , above which the absolute instability is predicted, relaxation of pressure anisotropy is observed for the first time by use of an array of diamagnetic loops together with a Faraday cup and secondary-electron emission detectors.PACS numbers: 52.35.Qz, 52.50.Gj, 52.55.Jd Generation of an Alfven ion-cyclotron (AIC) instability is expected in a magnetized plasma with strong pressure anisotropy. However, there have been limited experimental works, especially in laboratory plasmas. The first experimental evidence of the AIC mode was performed in the end cell of the TMX tandem mirror [1,2]. A high p± (the ratio of the perpendicular plasma pressure to the magnetic field pressure) plasma with strong pressure anisotropy is produced by intense neutral-beam injection (NBI) in the direction perpendicular to the magnetic field line at the midplane of the minimum-/? mirror field. The AIC mode was also observed in an ion-cyclotron-rangeof-frequency-(ICRF-) heated plasma in the central cell of the TAR A tandem mirror [3]. The interaction between alpha particles and the generated Alfven modes is going to be a critical subject for future fusion devices. Effects of the AIC mode on the plasma parameters were described precisely in computer simulations [4][5][6][7]. Also, rapid pitch angle scattering due to the AIC mode has been simulated in a space plasma [8]. Relaxation of the pressure anisotropy is predicted theoretically; however, a direct observation of the relaxation due to the generation of the AIC mode has not been reported in laboratory plasmas.In this Letter we report a parametric study of the AIC fluctuation for a wide range of the anisotropy parameter, in order to compare with an available theory. We report the first observations of the anisotropy relaxation associated with the AIC mode in the ICRF-heated central cell plasma of the GAMMA 10 tandem mirror.GAMMA 10 is a minimum-/? anchored tandem mirror with axisymmetric plug/thermal-barrier regions at both ends [9,10]. The central cell is 5.6 m long with a field strength of 0.4 T at midplane. The mirror ratio is 5. The diameter of the limiter which is set near the midplane of the central cell is 0.36 m. Double half-turn antennas are located near the end of the central cell for ion heating at the fundamental ion-cyclotron resonance layer near the midplane. So-called Nagoya type-Ill antennas [11] are installed on the outer side of the double half-turn antennas. They are used for producing and sustaining a plas-ma, together with hydrogen gas puffing into the central cell and short-pulse (1 ms) plasma guns at both ends [12]. In the present experiment, no other heating systems such as electron-cyclotron heating (ECH) and NBI a...

Microwave power, P ECH < 140 kW, has been injected at 28 GHz into the axisymmetric plug/barrier cell in the axisymmetrized tandem mirror GAMMA 10. As observed by soft X-ray measurements, the microwaves generate a hot (50-60 keV) electron population, radially peaked on the magnetic axis, which results in the formation of a thermal barrier. The production mechanism of these hot electrons is found to be second harmonic electron cyclotron heating (ECH), corrected for the effects of the relativistic mass variation and the Doppler shift. This mechanism also explains the first experimental observation of a saturation of the single-component hot electron temperature T eh as being caused by the finite width of the incident microwave lobe. The dependence of the plasma parameters on the filling gas pressure, the plasma density and the ECH power is studied. It is found that the heating process can be interpreted as a competition between electron acceleration by the incident wave, electron deceleration by collisions, and the mirror trapping efficiency of the source electrons for hot electrons. The axial profile of the soft X-rays is investigated in relation to the mechanism of the second harmonic ECH. The heating process is discussed in terms of the electron pitch angle and the magnetic field intensity.

Few studies have compared how rehabilitative post-acute care affects recovery of walking ability and other functions after stroke in different age groups. After propensity score matching (1:1), 316 stroke patients were separated into an aged group (age ≥65 years, n=158) and a non-aged group (age <65 years, n=158). Both groups significantly improved in Barthel index, EuroQol-5 dimension, Berg balance scale, 6-minute walking distance and 5-meter walking speed ( P <0.001). The non-aged group had significantly larger improvements in Berg balance scale, instrumental activities of daily living, EuroQol-5 dimension and 6-minute walking distance ( P <0.001) compared to the aged group. The two groups did not significantly differ in Barthel index, 5-meter walking speed, length of stay, and cost. The aged group had poorer walking ability and poorer instrumental activities of daily living compared to the non-aged group. After intensive rehabilitative post-acute care, however, the aged group improved in walking ability, functional performance and mental health. Intensive strength training for unaffected lower limbs in the stroke patients achieved good recovery of walking ability and other functions. Overall, intensive rehabilitative post-acute care improved self-care ability and decreased informal care costs. Rehabilitative PAC under per-diem reimbursement is efficient and economical for stroke patients in an aging society.