I have a serious hobby coilgun project powered by a 6S (25V) LiPo Battery. Currently i have the LiPo, capable of at least 600A burst current connected to a ~75mOhm circuit for some 300+A of peak current. I have built said system with a Mosfet switch (AUIRFB8409 ~1.4$ each from AliExpress). These have worked, but if the current stays on even a little longer (or maybe vene from just wear) they break. The first switch is exposed to some ~4-8 ms of current, which according to my calculations would only rise to the 300A at the 4ms mark or so (pure speculation).
My question: What are my best alternatives to switch the current?
As i see it:
Parallel 2-4 of those mosfets with strong thermal coupling. Cheapish, would probably work?
IGBT? The high voltage rating is wasted and would not work properly with my 25V? and they seem to either have same current handling as Mosfets or be super expensive and huge
Something else entirely?
Thank you for your time