trigger_tractorbeam
trigger_tractorbeam is a brush entity available in the following 
Source games or engine branches:
Portal 2 and 
Portal 2: Community Edition.
…
It is a trigger is emitted from a prop_tractor_beam and works with a projected_tractor_beam_entity to create an anti-gravity state for the player, and to pull/push the player away/towards the funnel model.
Warning:This entity will crash the game if manually created in Hammer!