which in turn are connected to the various gas supply arrangements shown generally at 224 226 and 228 the vacuum pumps 42 44 are shown connected to cross linking duct 40 while it will be appreciated that various forms of gas supply may be employed the readers 39 attention is drawn to an evaporator arrangement at 224 in which an evaporator 230 is provided to evaporate a source of liquid diamond like component from injection mechanism 232 this injection mechanism supplies a small amount of liquid which is completely vaporized in the heated flash evaporator 224 an inert carrier gas such as argon or nitrogen can be added to help transport the vaporized liquid to the chamber item 226 illustrates a heater arrangement 234 in which a precursor liquid is heated to a temperature where it has a certain vapor pressure a carrier gas is then u201c bubbled u201d through the heated liquid such that the gas bubble picks up an amount of precursor liquid as the ratio of the vapour pressure of the liquid at that temperature and pressure over the total pressure in the bubbler a sublimer can also be used in the case of a solid precursor in this case the solid is heated to generate a certain vapor pressure and a carrier gas is used to move the precursor gas to the chamber item 228 discloses a still further arrangement in which sources of pressurized gas shown generally at 238 is supplied via mass flow controllers shown generally at 240 and then directed to connections 220 and or 222 a biasing system is shown generally at 242 and includes a source of dc power and a pulsing mechanism connected to the workpiece 12 and anode 76 as shown diagrammatically in fig1 a control computer.