| Abstract from DBPedia | The beta of a plasma, symbolized by β, is the ratio of the plasma pressure (p = n kB T) to the magnetic pressure (pmag = B²/2μ0). The term is commonly used in studies of the Sun and Earth's magnetic field, and in the field of fusion power designs. In the fusion power field, plasma is often confined using strong magnets. Since the temperature of the fuel scales with pressure, reactors attempt to reach the highest pressures possible. The costs of large magnets roughly scales like β½. Therefore, beta can be thought of as a ratio of money out to money in for a reactor, and beta can be thought of (very approximately) as an economic indicator of reactor efficiency. For tokamaks, betas of larger than 0.05 or 5% are desired for economically viable electrical production. The same term is also used when discussing the interactions of the solar wind with various magnetic fields. For example, beta in the corona of the Sun is about 0.01.ベータ値（ベータち）は、プラズマの圧力のに対する比である。太陽や地球の磁場、また核融合において用いられる用語である。 核融合の分野では、プラズマは巨大な超電導電磁石によって閉じ込められている。プラズマの温度は圧力と対応するものであり、核融合炉内ではプラズマは高圧になる。電磁石のコストはおよそβ½に比例し，核融合炉の経済性を表す指標となる。経済性を満たす炉を作るためには少なくとも5%のベータ値が必要となる。 (Source: http://dbpedia.org/resource/Plasma_beta) |
