deflector

Something which deflects something else, especially a stream of fluid or particles.

1992 Nasa Patents Available for Licensing from the George C. Marshall Space Flight Center The deflector assembly contains a plurality of vanes which change the direction of the solar energy to the vertical, while constantly keeping the same side of the deflector facing the sun.

A diaphragm in a lamp, stove, etc. by which the flame and gases are brought together to improve combustion.

A force field; an invisible barrier used as a protective shield.

The blasters are those beams of ravening destruction which take care of recalcitrant meteorites in a spaceship's course when the deflectors can't handle them.

Deflectors say there's something there, sensors say there isn't. Density negative. Radiation negative. Energy negative.