Ehhhhhh.....never happen and I odn't know if it would help much anyway. A little background on it - radar services around Lafayette used to be handles by the controllers at Grissom AFB - they have radar coverage around LAF down to the ground basically. Don't know why they don't do it anymore but it's now a function of Chicago or Indy center(don't remember which one it is) but their radar coverage isn't nearly as good. If anything happens "approach control" services would probably be transfered back to Grissom. Lafayette simply doesn't have the IFR traffic to warrant their own radar service nor do they have the physical facilities to house it.
You'll find that very very few towers have radar in the tower unless it's at a fairly busy IFR airport and the tower controllers sometimes work approach control simultaneously. Remember that a tower controller's job is to seperate traffic ON the runway - nothing more than that. Their job is not to seperate traffic in the airspace surrounding the airport - especially that airspace outside of the Class D. The main problem is that Purdue needs to develop a better 'deconfliction' plan. I assume they're still doing that 'even tails go north odd go south' thing - that's fine but often students(especially new students that aren't that familiar with the area) interpet that to mean they either go DUE NORTH or DUE SOUTH and you end up with a gaggle of airplanes doing manuevers 8 miles due north or 8 miles due south of the field. Instructors need to do a better job of defining the practice area with their students and let them know that it's ok to go to the northwest or the southeast, etc. etc..
Another problem area is the VFR check-in points.Instructors tend to show students the SIA plant and the Great Lakes building and then students tend to fly directly over those points and call the tower. There's nothing wrong with calling the tower "3 miles abeam SIA".
I think the chances of LAF getting radar are not that great and like I said before I don't know for sure that it would help all that much - there are other, simpler things that could be done to help a great deal.
Jason