Development of effective power supply using electric double layer capacitor for static magnetic field coils in fusion plasma experiments

A cost-effective power supply for static magnetic field coils used in fusion plasma experiments has been developed by application of an electric double layer capacitor (EDLC). A prototype EDLC power supply system was constructed in the form of a series LCR circuit. Coil current of 100 A with flat-top longer than 1 s was successfully supplied to an equilibrium field coil of a fusion plasma experimental apparatus by a single EDLC module with capacitance of 30 F. The present EDLC power supply has revealed sufficient performance for plasma confinement experiments whose discharge duration times are an order of several seconds.     

Stochastic Resonance and Coincidence Detection in Single Neurons

We demonstrate that a realistic neuron model expressed by the Hodgkin-Huxley equations shows a stochastic resonance phenomenon, by computing cross-correlation between input and output spike timing when the neuron receives both aperiodic signal input of spike packets and background random noise of both excitatory and inhibitory spikes. We consider that such a signal detection is realized because the neuron with active properties is sensitive to fluctuation caused by a sharp increase just after a sudden dip of excitatory noise spikes and a gradual decrease of inhibitory noise spikes. We also show that the model generates highly irregular firing of output spikes on the basis of the modulation detecting property.     

Development of multi-channel Doppler spectroscopic measurement system using 8 × 8 multianode photomultiplier tube assembly

Using an 8 × 8 channel photomultiplier tube assembly and a single Czerny-Turner monochromator, we have developed a novel Doppler spectroscopic system which can measure the time evolutions of spectral distribution of plasma emission from eight different lines of sight simultaneously. An optical lens system is employed to couple the output of the monochromator with the detector assembly, resulting in small cross-talks less than 5% in spatial distribution together with large magnification of up to 50 in wavelength direction. The suggested system yields cost-effective polychromatic measurements of eight spatial channels with uniform optical and electrical characteristics.