Nozzle and liquid ejection system

A nozzle for spraying a liquid on an object, the nozzle comprising:

• a first portion including a first flow channel and a first inner wall surface that defines the first flow channel, the first flow channel including a first inlet through which the liquid enters the first flow channel and a first outlet through which the liquid exits the first flow channel;
• a second portion being joined to the first portion and including a second flow channel and a second inner wall surface that defines the second flow channel, the second flow channel being continuous from the first flow channel, the second flow channel having an inner diameter less than an inner diameter of the first flow channel, the second flow channel including a second inlet through which the liquid enters the second flow channel and a second outlet through which the liquid exits the second flow channel, the second inlet having an inner diameter less than an inner diameter of the first outlet of the first flow channel;
• a third portion being joined to the second portion and including a third flow channel and a third inner wall surface that defines the third flow channel, the third flow channel being continuous from the second flow channel, the third flow channel including a third inlet through which the liquid enters the third flow channel and a third outlet through which the liquid exits the third flow channel, the third inlet having an inner diameter greater than an inner diameter of the second outlet of the second flow channel, the third flow channel including:
• a diameter-decreasing section having an inner diameter gradually decreasing from the third inlet toward the third outlet;
• and
• a straight section being between the diameter-decreasing section and the third outlet, the straight section having an inner diameter less than the inner diameter of the second outlet of the second flow channel, wherein
• the second portion includes a step surface that connects the second inner wall surface of the second portion to the third inner wall surface of the third portion,
• the diameter-decreasing section extends from the step surface such that the second flow channel, the step surface, and the diameter-decreasing section are continuous, and
• the third inner wall surface of the diameter-decreasing section is directly continuous from the step surface.