Is there a standard IPA equivalent of the gargle-ish sound you make when you clear phlegm out of your throat, like when you pronounce 'Achmed', where the 'ch' is the 'phlegm' sound?
The OP has clarified the question in comments, so I'll try to provide an actual answer.
like when you pronounce 'Achmed' where the 'ch' is the 'phlegm' sound.
My understanding is that the name is not correctly pronounced with the throat-clearing ch sound, but people are familiar with hearing that and the intent is clear.
The throat clearing sound in these words is the voiceless velar fricative /x/ (IPA symbol is English letter x). See Wikipedia discussion with recording