Paddle configuration for a particle coating reactor
A reactor for coating particles includes a stationary vacuum chamber to hold a bed of particles to be coated, a chemical delivery system, and a paddle assembly. The paddle assembly includes a rotatable drive shaft and a first plurality of paddles and a second plurality of paddles that extend radially from the drive shaft. The spacing, cross-sections, and oblique angles of the paddles are such that orbiting of the paddles causes the first plurality of paddles and the second plurality of paddles to displace substantially equal volumes in opposite directions in the lower portion of the stationary vacuum chamber.
1. 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.
2. The reactor of claim 1 , wherein the outer curvature of the first cross-section matches an inner curvature of the lower portion of the stationary vacuum chamber.
3. The reactor of claim 2 , wherein the outer curvature of the first cross-section is parabolic.
4. The reactor of claim 2 , wherein a spacing between the outer curvature of the first plurality of outer paddles and the inner curvature of the lower portion of the stationary vacuum chamber is less than 1.5 millimeters.
5. The reactor of claim 1 , wherein the second plurality of inner paddles are positioned and oriented such that orbiting of the second plurality of inner paddles results in no dead zone in the bed of particles in the lower portion of the stationary vacuum chamber.
6. The reactor of claim 5 , wherein a number of inner paddles of the second plurality of inner paddles and the second cross-section of each inner paddle result in dead zones in the bed of particles of less than 5% of the lower portion of the stationary vacuum chamber when the second plurality of inner paddles orbit about the axial axis.
7. The reactor of claim 1 , wherein the first plurality of outer paddles oriented at the first oblique angle drives particles in a first direction along the axial axis and the second plurality of inner paddles oriented at the second oblique angle drives particles in a second direction along the axial axis opposite to the first direction.
8. The reactor of claim 7 , wherein the first oblique angle and the second oblique angle and the first cross-section and second cross-section are each displace a same volume in the lower portion of the stationary vacuum chamber when the second plurality of inner paddles and first plurality of outer paddles orbit about the drive shaft.
9. The reactor of claim 8 , wherein the first oblique angle and the first cross-section, and the second oblique angle and the second cross-section of the second plurality of inner paddles and first plurality of outer paddles, respectively, results in no scooping action by respective paddles of the plurality of paddles when the plurality of paddles orbit about the drive shaft.
10. The reactor of claim 8 , wherein the first oblique angle and the first cross-section, and the second oblique angle and the second cross-section of the second plurality of inner paddles and first plurality of outer paddles, respectively results in a change in a bed surface angle of the bed of particles with respect to an initial level of less than 2 degrees after a rotation of the drive shaft about the axial axis.
11. The reactor of claim 1 , wherein at least a first portion of a first cross-sectional area of each of the first plurality of outer paddles overlaps with at least a second portion of a second cross-sectional area of each of the second plurality of inner paddles along the axial axis.
12. The reactor of claim 11 , wherein a third portion of each outer paddle of the first plurality of outer paddles overlaps with a fourth portion of another outer paddle perpendicular to the axial axis.
13. The reactor of claim 12 , wherein a fifth portion of each inner paddle of the second plurality of inner paddles overlaps with a sixth portion of another inner paddle of the second plurality of inner paddles perpendicular to the axial axis.
14. The reactor of claim 13 , wherein the plurality of paddles are positioned and oriented such that orbiting of the plurality of paddles results in a dead zone in the lower portion of the chamber of less than 5% of the lower portion.
15. The reactor of claim 13 , wherein the plurality of paddles are positioned and oriented such that orbiting of the plurality of paddles results in a dead zone in the lower portion of the chamber of less than 3% of the lower portion.
16. The reactor of claim 13 , wherein the plurality of paddles are positioned and oriented such that orbiting of the plurality of paddles results in a dead zone in the lower portion of the chamber of less than 1% of the lower portion.
17. 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 and a spacing of paddles about the drive shaft substantially eliminates a dead zone from the lower portion of the chamber.