An isolated, isothermal, and wide magnetic flux tube embedded either in the solar chromosphere or in the lower solar corona is considered, and the propagation of linear torsional Alfv'en waves is investigated. It is shown that the wideness of the tube leads to a new cutoff frequency, which is a local quantity that gives the conditions for the wave propagation at different atmospheric heights. The cutoff is used to establish the ranges of frequencies for the propagating and reflected waves in the solar chromosphere and lower solar corona. The obtained results are compared to those previously obtained for thin magnetic flux tubes and the differences are discussed. Moreover, the results are also compared to some current observational data, and used to establish the presence of propagating waves in the data at different atmospheric heights; this has profound implications on the energy and momentum transfer by the waves in the solar atmosphere, and the role of linear torsional Alfv'en waves in the atmospheric heating and wind acceleration.

中文翻译：

---

沿宽太阳磁通管传播的扭转 Alfv́en 波的新截止频率

考虑了嵌入在太阳色球层或较低日冕中的隔离、等温和宽磁通量管，并研究了线性扭转阿尔芬波的传播。结果表明，管的宽度会导致新的截止频率，这是一个局部量，给出了波在不同大气高度传​​播的条件。截止用于确定在太阳色球层和较低日冕中传播和反射波的频率范围。获得的结果与先前获得的薄磁通管的结果进行了比较，并讨论了差异。此外，结果还与一些当前的观测数据进行了比较，并用于确定不同大气高度数据中传播波的存在；