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Detached plasma control by H- / D- negative ion in divertor simulator
akira Tonegawa,Hiroyuki YAZAWA,Kazutaka KAWAMURA,Masataka ONO,Syusaku MAETA 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
We have developed a new way to stably maintain a detached hydrogen or deuterium plasma based on feedback control of the relative negative-ion (H.or D.) density in the linear divertor plasma simulator, TPD-SheetIV. Measurements of the relative negative ion density, nH.or nD., heat load to the target plate, Q, and the secondary gas-flow rate, Gdiv, were carried out as a function of neutral pressure in the plasma. The detached plasma is steadily maintained in the region of the target plate by rapidly varying Gdiv so as to maximize the value of the n.Hor n.Dand to keep the gas pressure constant. The new system has achieved the goal of reducing both Q and the amount of Gdiv in a detached plasma without radiative and three-body recombination processes.
Observation of disossiative recombination in the hydrogen sheet plasma
akira Tonegawa,Hiroie MATSUMOTO,Hiroyuki YAZAWA,Kazutaka KAWAMURA,Masataka ONO,Takehisa SHIBUYA 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
The experimental observation of dissociative recombination in Molecular Assisted Recombination (MAR) for hydrogen detached plasma has been studied in the linear divertor plasma simulator, TPD-SheetIV. Measurements of the relative concentrations of atomic and molecular ions (nH+, n+ H2, and n+ H3), electron density (ne), electron temperature (Te), and heat load to the target plate (Q) were carried out in hydrogen detached plasma with hydrogen gas puff at varying discharge current. An “omegatron” mass analyzer, situated behind a small hole of the endplate, is used for analyzing ion species. It is shown from these results that the dominant molecular process is a dissociative recombination process via H+ 2 , H+ 3 in the plasma over the range of low plasma density (<5 × 1018 m.3) and low hydrogen pressure (<4 mTorr). In contrast, molecular assisted dissociation (MAD) always dominates over the MAR in the high density plasma (>5 × 1018 m.3).
Enhancement of Learning and Memory by Elevating Brain Magnesium
Slutsky, I.,Abumaria, N.,Wu, L.J.,Huang, C.,Zhang, L.,Li, B.,Zhao, X.,Govindarajan, A.,Zhao, M.G.,Zhuo, M.,Tonegawa, S.,Liu, G. Cell Press 2010 Neuron Vol.65 No.2
Learning and memory are fundamental brain functions affected by dietary and environmental factors. Here, we show that increasing brain magnesium using a newly developed magnesium compound (magnesium-L-threonate, MgT) leads to the enhancement of learning abilities, working memory, and short- and long-term memory in rats. The pattern completion ability was also improved in aged rats. MgT-treated rats had higher density of synaptophysin-/synaptobrevin-positive puncta in DG and CA1 subregions of hippocampus that were correlated with memory improvement. Functionally, magnesium increased the number of functional presynaptic release sites, while it reduced their release probability. The resultant synaptic reconfiguration enabled selective enhancement of synaptic transmission for burst inputs. Coupled with concurrent upregulation of NR2B-containing NMDA receptors and its downstream signaling, synaptic plasticity induced by correlated inputs was enhanced. Our findings suggest that an increase in brain magnesium enhances both short-term synaptic facilitation and long-term potentiation and improves learning and memory functions.