Patent ID: 7866188

Claim:
A PCVD apparatus, comprising: (i) a cylindrical applicator having an inner cylindrical wall defining an interior cylindrical space, the interior cylindrical space itself defining a central, cylindrical axis; (ii) a microwave generator that produces microwave energy at a wavelength λ; (iii) a waveguide for transmitting the microwave energy to said applicator; and (iv) a choke at least partly defined within said applicator, wherein the length of said choke (l) is defined in accordance with the following equation: l=b−a, wherein a=the radius of said applicator's inner cylindrical wall as measured from the central, cylindrical axis defined by said applicator's cylindrical interior space, and b=the overall length of said choke as measured from the central, cylindrical axis defined by said applicator's cylindrical interior space; and wherein the length of said choke (l) is less than the length of a theoretical quarter-wavelength choke in accordance with the following equation: (0.60 L λ/4 )≦ l ≦(0.89 L λ/4 ), wherein L λ/4 =the length of the theoretical quarter-wavelength choke as defined in accordance with the following equation: L λ/4 =b′−a, wherein a=the radius of the applicator's inner cylindrical wall as measured from the central, cylindrical axis defined by the applicator's cylindrical interior space, and b′=the calculated overall choke length of the theoretical quarter-wavelength choke as derived, in the cylindrical coordinate system, from the following equations: H 0 ( 2 ) · ( k 0 · n · b ′ ) H 0 ( 1 ) · ( k 0 · n · b ′ ) = H 1 ( 2 ) · ( k 0 · n · a ) H 1 ( 1 ) · ( k 0 · n · a ) H v (1) , H v (1) =Hankel functions, n=refractive index of choke filler material, if any, and k 0 =wave number in a vacuum of the microwave energy having a wavelength λ, where k 0 = 2 · π · f c 0 f=frequency of the microwave energy, and c 0 =velocity of light in a vacuum.