I never even thought to just search for Plasma cutter connectorNeed dimensions really but this may fit the bill.
2Pins Socket Connector Fit Air Plasma Cutter Cutting Torch and TIG Welding Torch | eBay
1pcs 2 pin socket connector. 1pcs 2 pin connector. and we will send you an invoice.www.ebay.co.uk
This series of connectors is widely used in radio equipment for power (2 pole) and microphone connections (more poles) so any amateur radio supplier should be able to help. Maplin is still around for mail order. Note some TIG units use XLR connectors for the switch and foot peddle I’ve seen them sold for more than £20 for welders, you can get the best quality Neutrik ones from studio suppliers for about £3 they’re used a lot in pro audio kit.