Plasmas in machines with all metal plasma facing components have a lower Zeff. less radiation cooling in the scrape-off layer and divertor regions and are prone to impurity accumulation in the core. Higher gas puff and the seeding of low-Z impurities are applied to prevent impurity accumulation. to increase the frequency of edge localised modes and to cool the divertor. https://atlanticknifers.shop/product-category/factory-second/