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Various probing beams have been developed and used for plasma diagnostics in thermonuclear fusion research for magnetic confinement The required beam current, beam size, energy, beam characteristics such as divergence, energy spread, and emittance, etc., as well as ion species are different depending on the purpose of diagnostics, target plasma size and parameters. Hydrogen beams are used for charge-exchange recombination spectroscopy (CHERS) and motional stark effect (MSE) spectroscopy. Suitable beam energy for CHERS ranges in the area of 50 keV/amu, and a small beam divergence is required for MSE measurements. Heating beams are often used as diagnostic beams by sharing. Neutral lithium probing beams have been used as effective tools for measurement of density and fluctuations. A heavy ion beam probe (HIBP), made from alkali metal ions, is injected directly without neutralization to measure plasma potential and density, as well as their fluctuations. Recent progress in magnetic fusion experiments has resulted in advancement of the development of negative ion sources, such as He¯ and Li¯ sources for alpha-particle measurement, because of their advantages with regard to efficient neutralization in the high-energy region, and an Au¯ source for HIBP with the application of tandem acceleration. [ABSTRACT FROM AUTHOR]

In recent years, optical parametric chirped-pulse amplification (OPCPA) has emerged as a powerful tool for the generation of ultrashort pulses with extreme peak intensity. It has enabled the generation of phase-controlled few-cycle pulses in widely different parts of the spectrum. For the near-infrared spectral range, OPCPA is becoming an interesting alternative to conventional Ti:Sapphire-based laser technology for various applications. In this paper, we discuss the physics behind OPCPA, as well as the practical design considerations for the development of high-intensity, phase-stable few-cycle OPCPA systems. Also, we review the experimental achievements in ultrafast OPCPA systems to date. [ABSTRACT FROM PUBLISHER]

A weighted-sum (WS) function computes the sum of selected integers. This paper considers a design method for WS functions by look-up table (LUT) cascades. In particular, it derives upper bounds on the column multiplicities of decomposition charts for WS functions. From these, the size of LUT cascades that realize WS functions can be estimated. The arithmetic decomposition of a WS function is also shown. With this method, a WS function can be implemented with cascades and adders. [ABSTRACT FROM AUTHOR]

The most critical demand for high-brightness ion beams emerged from the realm of industrial applications of focused ion beams and it was met by using liquid metal ion source technology. Although recognized as a successful technology, liquid metal ion sources have major limitations in view of beam species. Noncontaminating ion beam species with beam brightness comparable to liquid metal ion source, i.e., ∼ 106 A cm¯² sr¯¹ and energy spread of ∼ 1 eV will be ideal for many cutting-edge applications including ion beam milling, mask repair, and imaging studies. This paper attempts to bring out the essential points in the development of high-resolution probe forming beams. With this specific objective in view, this study is based on an analysis of point sources and then a variety of other sources, under the general classification of "broad" source (primarily plasma sources), are discussed. Several sources in this category including a Penning-type source, a multicusp source, and new-generation high-charged state sources seem to have merits for circumventing the limitations of liquid metal ion sources, although further re- search is needed to improve the beam brightness and advance the state-of-the art. [ABSTRACT FROM AUTHOR]

Reduction of magnetic islands induced by an error field is essential to achieving high-performance plasmas in helical/stellarator systems. Magnetic islands were observed in the large helical device by applying a fluorescent technique with an electron gun and a fluorescent mesh. Two stripes of impurity line emission profiles were observed with a tangentially viewing fast-framing charge coupled device (CCD) camera during the termination phase of the plasma discharge. A three-dimensional calculation of magnetic field lines on the magnetic island shows that the two stripes correspond to the magnetic islands. The images of the impurity line emission can contribute to identifying magnetic islands and the investigation of the physical mechanisms of plasma confinement in the island. [ABSTRACT FROM AUTHOR]