Orghast was a language invented by Ted Hughes to be used in his 1970s play of the same name, performed in Persepolis, Iran in 1971. The theatre director Peter Brook, who collaborated with Hughes, was interviewed a few days ago on the Radio 4 Today programme (listen here; the interview is at 2:22:14).
Brook said that they had come to feel that languages lost part of their richness over time, and that ancient languages contained more vibration and tonality, which contributed to a greater richness. Therefore, Hughes agreed to sit and wait over a sheet of paper until a primal word arose from within him. The name Orghast is supposed to have arisen in this way, and means 'sun'.
There is a snippet of the language on the Today interview, which you can hear in full at 2:22:14 here.