Well, I'm not exactly sure, what you mean with "intensity", but if you mean the thicknes of the plot line, you can go down to "Polar Plot.vi" --> "Plot Polar Data.vi" and on "Draw Multiple Lines.vi" you can create at the input [Pen] a constant to set the line Width to something greater than 1.
Does this help?
greets, Dave
P.S. And YES, I also was absolutely exalted about the Polar Plot.vi, it is great work by NI.
Greets, Dave