With the Selection Tool, select the point on the right side of that circle and drag it out to the right. Select the Convert Anchor Point tool (Shift+C) and click on the anchor point you dragged to get rid of the handle bars and make it a sharp corner. Do the same to the other corner.
With the shape still selected, go to Effects>Warp>Flag and set the horizontal bend slider to 100 per cent. Select Window>Brushes and open the Brush palette. Move this new shape to the brushes window and select it as a new art brush.
Start drawing a few shapes as shown and apply the brush you have just created. Try to make smooth lines and change the stroke size if needed. Copy your best shapes to Photoshop and go to Layer>Style>Outer Glow, and change the size to 150px and the blend mode to Colour Dodge.