How to draw arched concentric lines...

[nullpointer]

I'm doing a drawing and I ran across this image that had the precise background lines I was in search of. They are the arched lines in the upper half of the circle.

Any ideas as to how I can recreate this effect?

Thanks!

[spinhead]

Brief overview of one possible method, assuming they are segments of concentric circles, meaning they follow the same arc, and ending with a pixel image, not vectors:

1. create a donut to match the innermost arc. give it an hole radius of 98%.
2. duplicate it. increase size by 10%. change hole radius to 97%.
3. repeat as often as you need.
4. use geometry to add them together.
5. make a selection top-aligned with the image using the circle marquee a bit smaller than the outermost donut to slice off the edges like your example.
6. invert the selection, rasterize everything, hit delete.

You'll have to play with the numbers to make it exactly what you want. I just made these up as a quick demo.

If you need a vector version, I'm too tired to sort out steps 5 and 6 but someone more experienced or awake can certainly help.

[G13RL]

You can try to use a spiral to which you have applied pressure.
As AD does not have a spiral tool, I created one with Xara, exported as an svg. I applied the pressure in AD.
I tilted the spiral slightly to try to give the illusion of concentric circles.