200nH 120A inductor

If this is a filter just to remove RF, how about using mumetal formed to go around the bus bar?

There may be either C cores or a combination of C cores and I cores that can suitably encircle your flat bars. I have gotten ferrite cores by Philips Magnetic Components (formerly Ferroxcube), distributed by Eastern Components. Last time I needed some (a few years ago), minimum order requirements were tolerable.

- Don Klipstein ( snipped-for-privacy@misty.com)

How about ferroxcube u15/11/6 cores?

I think All Star Magnetics stocks them

Get miitary: Air Corps (air core); 120 amps has a tendency to saturate any ferrite you would like to mention, unless the size (cross-section) is huge. Yes, there are "flat" ferrite "bars"; most i have seen were for flat cable. Worthless at even 12 amps.. An air gap large enough to prevent saturation at 120 amps would not increase the inductance of a copper bar enough to be worth mentioning.

Mumetal is good at DC frequencies, not RF; formed around the bus bar would make a shorted turn which would tend to decrease inductance of the bus bar.

ar

I don't think it would. It has way more resistance than copper. At RF frequencies, it would look very lossy.

can some one please tell me what DC frequencies are?

The above statement is confusing me a bit.