Paddle configuration for a particle coating reactor

A reactor for coating particles, comprising:

• a stationary vacuum chamber to hold a bed of particles to be coated, the chamber having a lower portion that forms a half-cylinder and an upper portion;
• a vacuum port in the upper portion of the chamber;
• a chemical delivery system including a fluid passage through an aperture in a wall of the chamber to a deliver a precursor or reactant gas and a purge gas into the lower portion of the chamber, the aperture being located in the lower portion of the chamber;
• and
• a paddle assembly including
• a rotatable drive shaft extending through the chamber along an axial axis of the half cylinder,
• a plurality of paddles, including a first plurality of outer paddles and a second plurality of inner paddles, extending radially from the drive shaft such that the rotation of the drive shaft by a motor orbits the plurality of paddles about the drive shaft, wherein
• the first plurality of outer paddles comprise a first cross-section including an outer curvature and oriented at a first oblique angle,
• the second plurality of inner paddles comprise a second cross-section and oriented at a second oblique angle, and
• wherein the first cross-section and second cross-section and first oblique angle and second oblique angle are such that orbiting of the paddles causes the first plurality of outer paddles to sweep through and displace a first volume in the lower portion of the stationary vacuum chamber and the second plurality of inner paddles to sweep through and displace a second volume in the lower portion of the stationary vacuum chamber, and the first and second volumes are substantially equal.