Recent Progress in Plasma Control Studies on the Improvement of Plasma Performance in Heliotron J

Recent progress in plasma control studies on the improvement of plasma performance in Heliotron J is reviewed. The supersonic molecular beam injection （SMBI） fueling is successfully applied to Heliotron J plasma. A supersonic H2-beam is effectively injected to increase fueling efficiency and generate a peaked density profile. Local fueling with a short-pulsed SMBI can increase the core plasma density and avoid the degradation arising from edge cooling. Second harmonic electron cyclotron current drive （ECCD） experiments were conducted by launching a focused Gaussian beam with a parallel refractive index of -0.05 ≤ Nil 〈 0.6. Results show that the electron cyclotron （EC） driven current is determined not only by Nil but also by local magnetic field （B） structure where the EC power is deposited. Detailed analysis of the observed NI and B dependences is in progress with a ray-tracing simulation using the TRAVIS code. Fast ion velocity distribution was investigated using fast protons generated by ion cyclotron resonant frequency （ICRF） minority heating. For the standard configuration in Heliotron J, charge ex- change neutral particle analysis （CX-NPA） measurements show higher effective temperature of fast minority protons in the on-axis resonance case compared to that in the HFS （high field side） off-axis resonance case. However, the increase in bulk ion temperature in the HFS resonance case is larger than that in the on-axis resonance.

Present Status of the Nd:YAG Thomson Scattering System Development for Time Evolution Measurement of Plasma Profile on Heliotron J

A new high repetition rate Nd：YAG Thomson scattering system is developed for the Heliotron J helical device. A main purpose of installing the new system is the temporal evolution measurement of a plasma profile for improved confinement physics such as the edge transport barrier （H-mode） or the internal transport barrier of the helical plasma. The system has 25 spatial points with -10 mm resolution. Two high repetition Nd：YAG lasers （〉 550 m J@ 50 Hz） realize the measurement of the time evolution of the plasma profile with ~10 ms time intervals. Scattered light is collected by a large concave mirror （D----800 mm, f/2.25） with a solid angle of -100 mstr and transferred to interference filter polychromators by optical fiber bundles in a staircase form. The signal is amplified by newly designed fast preamplifiers with DC and AC output, which reduces the low frequency background noise. The signals are digitized with a multi-event QDC, fast gated integrators. The data acquisition is performed by a VME-based system operated by the CINOS.

Influence of Temperature, Moisture, and Light Conditions on the Germination of Seeds of <i>Erythronium japonicum</i>Decne

Erythronium japonicum is a representative species of spring ephemeral, forest floor plants in substitution forests in Japan. Seed germination tests were conducted to observe the effects of temperature, light, and moisture content on the germination of E. japonicum. E. japonicum seeds did not germinate at constant temperatures of 5&#176C, 10&#176C, 15&#176C, 20&#176C, or 25&#176C. Seeds germinated at 5&#176C and 10&#176C after storage at 20&#176C for 1 or 2 months. Seed germinability was affected by desiccation to only 40% moisture content. Seeds germinated well in both light and dark conditions. Conditions under the leaf litter layer showed unique characteristics of temperature, light, and moisture content. The temperature was around 20&#176C under the leaf litter layer, even though it was 30&#176C above. The moisture content under the leaf litter layer was higher than that above. The leaf litter blocked out the sunlight. The temperature of 20&#176C necessary for E. japonicum germination occurred below, but not above, the leaf litter layer. The avoidance of decreasing in germinability from reduced seed moisture content in a short time is consistent with the high moisture conditions under the leaf litter layer. The leaf litter layer plays an important role in providing optimal conditions of temperature, light, and moisture content for the germination of E. japonicum seeds.

Characterization of Full-WDM-Band Photodiode Modules Using Raman Amplifiers in the U Band at 40 Gb/s

We present the characteristics of a full-WDM-band photodiode module in 40 Gb/s U-band operation using a Raman amplifier. This module is suitable for wide-band transmission systems with the additional new channels in the U band.