Currently my cuurent is at 27A is ther a way to increase it?
Thanks.
You're not going to get more than 30 A with a 1.5 Ohms resistor and a 45 V voltage source (45V/1.5Ohm=30A). The extra 3 A are lost probably because of the FET's drain-source resistance, not sure what it is exactly in this simulation.
Another potential issue is that you're putting the load resistors between source and ground. What's the reason behind that? That may create issues if the gate driver's output is ground-referenced, because as the voltage drop on the load resistor increases, it will subtract from the gate-source voltage, preventing the FET from fully turning on as the current rises high enough.
In the latest simulation you connect the gate driving voltage source between the gate and source pins, so that's not an issue, but keep this in mind for the real circuit.
Additionally, this schematic is rather hard to read with all the wires ending nowhere and simulation-only primitives like current sources. I'd suggest drawing it in a more traditional way and use voltage sources as signal input.
I am working on something similar myself right now: a device that can provide short pulses of high current to a DUT, and it's also powered from a low-power source and has a bulk capacitor storing charge that can be quickly released when a trigger signal arrives. It simulates quite fine in ngspice, and I can't understand what your difficulty really is, because I can hardly understand the schematic.