Ultracold plasma expansion in a magnetic field

作者：Zhang X L^*; Fletcher R S; Rolston S L; Guzdar P N; Swisdak M

来源：Physical Review Letters, 2008, 100(23): 235002.

DOI：10.1103/PhysRevLett.100.235002

We measure the expansion of an ultracold plasma across the field lines of a uniform magnetic field. We image the ion distribution by extracting the ions with a high-voltage pulse onto a position-sensitive detector. Early in the lifetime of the plasma (< 20 mu s), the size of the image is dominated by the time-of-flight Coulomb explosion of the dense ion cloud. For later times, we measure the 2D Gaussian width of the ion image, obtaining the transverse expansion velocity as a function of the magnetic field (up to 70 G). We observe that the expansion velocity scales as B(-1/2), explained by a nonlinear ambipolar diffusion model with anisotropic diffusion in two different directions.

• 出版日期2008-6-13