Hi Skyeagle,
Comsol syntax is pretty much identical to that of Matlab (well they share plenty of history) ..... so for your equation you might try something like:
(10^7)*exp((10^3)*x^2)*(t<=2)
I'm assuming what you're after with the "x" is a cartesian coordinate (or that is how comsol would interpret from the above)? The "t<=2" evaluates as "1" for t <=2 (assuming your t is in seconds) and 0 otherwise (you can do the same thing with a simple "if"  construct or use several of the other available step  function  lookalikes, if you for example wish to smoothen the transition to 0 value).
