A grounded discharge wand with a round bulb on one end and a sharp point on the other is brought near a Van de Graaff generator. The bulb end draws out impressive sparks, while the pointed end produces only corona discharge.
Use the discharge wand to draw sparks from the dome.
Note: Be sure the discharge wand is physically touching the dome before turning it off.
1) CENPA has a High Voltage Engineering Corporation Model FN Tandem Van de Graaff Accelerator.