I have come up the big lift in the citadel, come through some passages jumped down a drop into a big hall. Here I killed some baddies and destroyed the big spidery thing with the energy balls from the two streams of them. Now I am stuck in the hall. I presume I somehow destroy the energy field at the far end. I have tried removing the energy balls, shooting energy balls at the glowing pillar thing and even throwing bits of broken spidery thing at it but nothing happens

Help