"Axial feedback stabilization of a flute mode in a simple mirror reactor, by M. A. Lieberman and S. L. Wong, Plasma Physics, Vol. 19, pp. 745-55 (1977). The article contains an L-C circuit that is unstable because the "capacitance" is negative: http://iopscience.iop.org/0032-1028/19/8/005/pdf/0032-1028_19_8_005.pdf
