Frequency power spectra are computed theoretically for shear Alfven waves excited in a solar coronal arcade by two separate perturbations, a cosine-modulated Gaussian perturbation and an impulsive driver. The arcade is assumed to consist of potential magnetic field lines embedded in a stratified plasma. It is shown that although the power spectra have discrete frequencies for each field line, a cumulative effect of many field lines of different widths/lengths in an arcade will be that of a continuous spectrum, if seen together as one entity. The nature of the frequency power spectra can constrain the size and the type of driver.

中文翻译：

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日冕拱廊中剪切阿尔文波频谱的性质

对于在日冕拱廊中由两个单独的扰动（余弦调制高斯扰动和脉冲驱动器）激发的剪切阿尔芬波，频率功率谱进行了理论上的计算。假定拱廊由嵌入分层等离子体中的潜在磁场线组成。结果表明，尽管功率谱对于每条场线具有离散频率，但如果将其视为一个实体，则拱廊中许多不同宽度/长度的场线的累积效应将是连续谱的累积效应。频率功率谱的性质可以限制驱动器的尺寸和类型。