Rl. Stenzel et Jm. Urrutia, Laboratory studies of magnetic vortices. I. Directional radiation of whistler waves based on helicity injection (vol 6, pg 2989, 1999), PHYS PLASMA, 6(12), 1999, pp. 4450
A novel principle for the directional excitation of whistler waves is demon
strated in a laboratory experiment. It is based on helicity conservation of
electron magnetohydrodynamic fields in plasmas. Whistler wave packets prop
agating in opposite directions to a static magnetic field have opposite sig
ns of helicity. Injection of helicity of one sign produces radiation in one
direction. This is accomplished with an antenna consisting of a loop linke
d through a torus. Directionality of 20 dB is readily achieved. The directi
on of radiation is electronically reversible. Transmission between two ante
nnas is unidirectional, hence nonreciprocal. Possible applications include
secure communication, direction finding, and efficient power deposition in
radio frequency (rf) heating. (C) 1999 American Institute of Physics. [S107
0-664X(99)01308-7].