Numerical measurements of the spectrum in magnetohydrodynamic turbulence

We report the results of an extensive set of direct numerical simulations of forced, incompressible, magnetohydrodynamic (MHD) turbulence with a strong guide field. The aim is to resolve the controversy regarding the power-law exponent (alpha, say) of the field-perpendicular energy spectrum E (k(perpendicular to)) proportional to k(perpendicular to)(alpha). The two main theoretical predictions alpha=-3/2 and alpha=-5/3 have both received some support from differently designed numerical simulations. Our calculations have a resolution of 512(3) mesh points, a strong guide field, and an anisotropic simulation domain and implement a broad range of large-scale forcing routines, including those previously reported in the literature. Our findings indicate that the spectrum of well-developed, strong incompressible MHD turbulence with a strong guide field is E (k(perpendicular to)) proportional to k(perpendicular to)(-3/2).