High-density microwave plasma source using negative-permeability metamaterial with tuned wave attenuation

High-density plasma generated by waves with efficient wave power consumption is suitable for various dry processes. However, when we use microwaves as power sources, the electron density in a conventional microwave plasma source is limited within the range in which the permittivity of the plasma is positive. To overcome this drawback, a negative refractive index phenomenon is applicable, in which the permittivity and permeability are both negative and microwaves can propagate even in a negative-permittivity space with high electron density. In this report, we demonstrate a promising scheme for the efficient generation of high-density plasma by propagating microwaves in a negative-permeability space, and show the experimental observation of the enhancement of plasma generation using the lower imaginary part of the permeability.