An ion sensitive probe (ISP) has been applied to ion diagnostics of the edge plasma of the GAMMA10 tandem mirror device. Since high energy ions are created by ion cyclotron range of frequency heating in the central cell of GAMMA10, a secondary electron repeller electrode is set in to suppress secondary electrons emitted from the collector due to high energy ions. Then secondary electrons are successfully suppressed. The ion flux flowing into the collector is evaluated with numerical calculation of ion orbits. This calculation includes the potential profile near the tip of the ISP. Then a correction factor F ␣ of the ion flux to the free streaming one is determined. The calculation yields V -I characteristic of the collector current. The ion density can be estimated by using the measured ion temperature and the factor F ␣ . Sample data of the ion temperature and the ion density in the edge region of the central cell of GAMMA10 are given. The measurement with the ISP shows that the edge ion temperature of GAMMA10 plasma ranges from 100 to 400 eV, and the ion density from 0.5ϫ 10 10 to 2 ϫ 10 10 cm −3 .

A -conjugated compound with two thioacetate end groups was synthesized using a recently developed method. A selfassembled monolayer (SAM) of corresponding dithiol was prepared by dipping a Au(111) surface for 1 min in a 2 mM dithiol toluene solution formed 30 min after the addition of a drop of 30% NH 4 OH in water to the dithioacetate toluene solution. We investigated electronic conduction through isolated single molecules of the -conjugated compound by statistical analysis of molecular junctions repeatedly formed between a gold tip and the SAM on Au(111) using scanning tunneling microscopy (STM) under ultrahigh vacuum (UHV). The single-molecular conductivity of the -conjugated compound is described as G m ¼ T contact with tip Á T -system Á T contact with substrate Á G 0 according to the Landauer equation. Here, Ts are transmission functions and G 0 is the quantum conductance, i.e., 2e 2 =h. Because of observed high values of G m for the -conjugated compound, we could readily analyze the effect of molecule-electrode contacts on T contact with tip Á T contact with substrate . Namely, we successfully observed the dependence of T contact with tip Á T contact with substrate on binding sites of -S À on a Au(111) surface, i.e., the bridge (or the hollow) and the top sites.

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The high power operation of gyrotrons exceeding their nominal powers has been carried out for ECRH at the plug region in the GAMMA 10 tandem mirror device. The highest recorded value of the axial ion confining potential for a hot ion mode plasma has been obtained. The mean energy T eff of the axially flowing electrons driven by the plug ECRH increases to 3 keV according to the increase in the heating power up to 260 kW. The maximum field-aligned potential difference ∆Φ has reached 5.5 kV and the scaling law between ∆Φ and T eff has expanded.