You’ll have to calculate points of a circle for each full turn of your spirale. The number of points depends on your desired segmentation, like 20points per turn, 5 turns, you need 96 points because the last point of one turn is the first point of the next turn. Each coordinate must be calculated by
X=r * cos (phi)
Y=r* sin (phi)
where phi=360/20 and then you would have to add z where z depends on the height of one turn. So Z=Number of current point * height / 20 + height * number of current turn
Then add these points to the spline.