x = r Cos[a]
y = r Sin[a]
z = a

p3d = Graphics3D[{
   Arrowheads[Table[0.03, {i, 1, 20}]],
   Hue[0.69, 0.67, 1.],
   Arrow[Table[{x, y, z/10} /. r -> 1, {a, 0, 8 Pi, 0.04}]~Tube~
     0.01]}, Axes -> True, AxesLabel -> {"x", "y", "z"}]

Export["test.jpg", p3d]

x = r Cos[a]
y = r Sin[a]
z = a

p3d = Graphics3D[{
   Arrowheads[Table[0.03, {i, 1, 20}]],
   Hue[0.69, 0.67, 1.],
   Arrow[Table[{x, y, z/10} /. r -> 1, {a, 0, 8 Pi, 0.04}]~Tube~
     0.01]}, Axes -> True, AxesLabel -> {"x", "y", "z"}]

Export["test.jpg", p3d]