MarkT:
[ BTW a single device will be enough if its something like this:
http://uk.farnell.com/ixys-semiconductor/ixfn140n20p/mosfet-n-sot-227b/dp/1427319
]
I agree the device can handle it. However Even with clean switching it will dissipate I^2 * R = 50^2 * 0.018 = 45Watts which is a lot of heat to get rid off. And a decent cooling blok is quite expensive. Now they have an experimental solution with 4 x mosfet generating about the same amount of heat. The cooling blok costs about a 100 euro's. So any alternative is welcome 