A large plasma fireball is formed using a reverse biased planar sputter magnetron source. The magnetic field considerably reduces the contact area of the anode with the plasma and results in the formation of the fireball. Ions are extracted from the fireball using a large voltage cathode sheath of the grounded sample holder. The physical mechanism for the extraction of the ions from the fireball along with the effect of the sample holder on the fireball and the discharge current is discussed. The device is shown as a novel tool for developing nanodot patterns on a GaSb substrate without the use of additional ion source or power supplies. Variable nanodot patterns produced simply by the alteration of discharge conditions demonstrate unique surface wettability and reflection properties.