Lower hybrid to whistler mode conversion on a density striation

When a wave packet composed of short wavelength lower hybrid modes traveling in an homogeneous plasma region encounters a density inhomogeneity, it can resonantly excite long wavelength whistler waves via a linear mechanism known as mode conversion. We study the linear mode conversion using a scalar-field formalism (in the limit of cold plasma linear theory) which we solve numerically [1]. We show that the linear mode conversion can effectively transfer a large amount of energy from the short to the long wavelength modes, and we study how the efficiency scales for different width and amplitude of the density striation. We present a general criterion for the width of the striation that, if fulfilled, maximizes the conversion efficiency. Such a criterion could provide an interpretation of recent laboratory experiments carried out on the Large Plasma Device at UCLA. \\[4pt] [1] E. Camporeale, G.L. Delzanno, P. Colestock, ``Lower hybrid to whistler mode conversion on a density striation,'' submitted to Journal of Geophysical Research (2012).