Q.Is corona more in AC or DC?

A.Corona Loss p = .00241[(f+25)/$]*[root of (r/d)]*square of[Vp-Vo]

f= supply frequency 

$= air density correction factor

Vp = operating voltage

Vo= critical disprutive voltage

r= radius of conductor

d= distance of separation for fine weather

Now for DC f=0, there is a certain power loss by corona but less than AC corona loss.