\psunit=1cm
\begin{pspicture}(-1,-1)(4.4,4.4)
%%%%%%%%%%%%%%%%%%%%Koordinaten
\psaxes[Ox=0,Dx=1,Oy=0,Dy=1,linewidth=0.1pt]{->}(0,0)(-0.2,-0.2)(3.5,3.5)%Schnittpunkt, x0, y0   x1,y1

\psarc(0,0){3cm}{0}{90} %(x,y  radius winkel1 winkel 2)
\psarc[linecolor=red](0,0){2cm}{0}{90}
\psarc[linecolor=green](0,0){1cm}{45}{90}
\end{pspicture}