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Improvement of the vertical stability of tokamak plasma with only local coils above and below the plasma was observed for the first time. The local coils in triangular shape, named upper and lower triangular (ULT) coils, were installed in TOKASTAR-2, a tokamak-stellarator hybrid device at Nagoya University. The ULT coils generate the effective radial magnetic field B R eff , which is expected to stabilize the plasma vertical position. The region of the plasma position where vertical displacement events (VDEs) did not occur was extended by applying the ULT magnetic field. Stabilization of the plasma vertical position was related to the ratio of the vertical-direction derivative of the effective radial field generated by the ULT coils, ∂ B R eff / ∂ Z , to that of the axisymmetric radial field, ∂ B R / ∂ Z . Moreover, even when VDEs occurred in discharges with the ULT magnetic field, the VDE speed was mitigated by the effect of the ULT magnetic field; the VDE speed increased with ∂ B R / ∂ Z , while decreased with ∂ B R eff / ∂ Z . [ABSTRACT FROM AUTHOR]

Scanning tunneling microscopy for semiconductor carrier profiling is simulated in three dimensions. By solving the tunnel currents between a probe tip and a sample consistently with the current continuity equations, current-voltage characteristics in good agreement with measurements are obtained. Critical differences from potential-based calculations are observed under depletion and inversion conditions. By preparing a current-concentration table from samples with uniform concentrations, the carrier profile in p-n junction samples can be extracted by estimating the concentrations at each position. It is revealed that the tunnel current is spread around the depletion region of a p-n junction, which affects the results dramatically. When a proposed simulation is iteratively used with measurements, impurity profile extraction is possible even in the depletion region. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the influence of electron temperature and of bias on charge build-up caused by electron shading in inductively-coupled plasmas at 2 to 40 mTorr in argon. Background on plasma charging damage to the gate-oxide of metal oxide semiconductor field effect transistors; Measurement of the electron and ion currents going into the silicon substrate through the dielectric structure; Effect of the electron temperature on the floating potential of the sample.

Demonstrates the use of oscillator-amplifier system for spectral narrowing of high-power D[sub2]O laser, in which a single-mode output from a compact D[sub2]O laser with a short cavity length was amplified by a large D[sub2]O laser amplifier. Significance of the spectral narrowing of an optically pumped high-power D[sub2]O laser; Differences of D[sub2]O laser from the conventional laser system; Maximum output energy of the D[sub2]O laser system.

Electron projection lithography (EPL) has been identified as a viable candidate of the next-generation lithography technologies for moderate-volume production of systems-on-a-chip for the sub-65 nm nodes. EPL is especially suited for the fabrication of contact structures. The development of a low-distortion mask is essential for meeting the stringent requirements at these lower nodes. This research focuses on quantifying in-plane distortions (IPDs) due to mask fabrication and the effects of different mounting schemes in the e-beam writer and exposure tools for a 200 mm EPL stencil mask. In order to quantify the IPD of the freestanding membranes, three-dimensional finite element (FE) models have been developed and benchmarked with experimentally measured data. Metrology measurements in both the membrane-side up and membrane-side down configurations can be used to correct for image placement errors (due to the fabrication and chucking of the mask) by compensating for IPD during the exposure process. To correct for higher order distortions associated with pattern specific errors, FE models were generated to simulate the entire process flow, including chucking. As a sample test case, a stencil pattern was replicated uniformly over the membrane arrays. The actual mask was fabricated and metrology measurements were taken. Selected membranes were experimentally measured to compare with FE results and the data correlated well in both direction and magnitude. Results illustrate that FE modeling and simulation can be used to predict mask distortions due to fabrication. Such techniques can be instrumental in meeting the stringent error budget required at the lower lithographic nodes. [ABSTRACT FROM AUTHOR]

The magnetohydrodynamic (MHD) activity and the discrete dynamo in high-Θ reversed-field pinch (RFP) discharges are studied through comparisons with those in normal-Θ RFP discharges, where Θ=Bθ(a)/ is the pinch parameter. In high-Θ RFP discharges, the mode coupling of m=1 is enhanced by the high magnetic shear configuration, and the MHD activity is more turbulent as compared with that in normal-Θ RFP discharges. Furthermore, the discrete increase of the toroidal magnetic flux is obviously observable. The increase of the toroidal magnetic flux generated by the discrete dynamo, which has an asymmetric structure in the toroidal direction, is only 1%–2% of the whole toroidal magnetic flux. The experimental results indicate that the discrete dynamo does not play an essential role in the RFP dynamo. [ABSTRACT FROM AUTHOR]

The radial electric field is driven to positive value by off-axis second harmonic electron cyclotron heating (ECH) in the Compact Helical System [Plasma Physics and Controlled Nuclear Fusion Research 1988, Nice (International Atomic Energy Agency, Vienna, 1989), Vol. II, p. 411]. The observed positive electric field is associated with the outward particle flux enhanced with ECH. The enhanced particle flux triggered by the production of the electrons accelerated perpendicularly to the magnetic field with ECH results in the change of the electric field. [ABSTRACT FROM AUTHOR]

Asserts that a reversed-field pinch (RFP) dynamo uniformly generates most of the toroidal flux in a RFP plasma with a high magnetic Reynolds number. Features of the global dynamo and magnetic fluctuations; Global dynamo and Taylor's theory; Mechanism of the global dynamo.

A rapid growth of magnetic fluctuations resulting from the m=1 and m=2 modes and succeeding stop of rotation of these modes have been found as the precursor phenomena of current termination in the STP-3(M) [Trans. Inst. Elec. Eng. Jpn. 107-B, 469 (1987)] reversed field pinch. By deepening the field reversal at the wall, these precursors disappear and the current duration becomes much longer. It is found that sudden current termination is caused by a rapid growth of resistive tearing modes mainly because of nonlinear coupling of the m=1 mode. [ABSTRACT FROM AUTHOR]

We describe the observation of stimulated emissions by current injections into a silicon quantum well. The device consists of a free standing membrane with a distributed feedback resonant cavity fabricated by state-of-the-art silicon processes. The emission spectra have multimode structures peaked in the near-infrared region above the submilliampere threshold currents at room temperatures. Consequently, electronics and photonics should be able to be converged on chips by using silicon quantum well laser diodes. [ABSTRACT FROM AUTHOR]