How do you get the Chrege Beam?

Go to the "Gathering Hall". Once there, make your way up to the top using the various platforms. Continue into a place called the "Energy Core." Turn left and enter the pipe on the bottom of the floor. Go through the network of pipes until you find a boss. Not too tough.

Mini-Boss - "Incinerator Drone"
This is a mini-boss, not a boss. Thus, things are a lot easier than they normally would be. The only attack is spewing out jets of flame, but you should watch out for the "War Wasps" in the indestructible hive above the machine. To attack the thing, all you have to do is wait until a red light appears above the machine. Hit that red button until it retracts. Continue in this fashion to defeat it. Once you defeat it you will get the bomb upgrade. Remember to scan both the "War Wasps" and the "Incinerator Drome" if you intend on scanning everythine!

The charge beam is in the watery hall. Its entrance is in the gathering hall across from save station 2. You have to scan 4 (or at least I think its 4) runic symbols around the room to open the door. Watch out for the blastcaps and reaper vines.