do_dump_fields_periodically Subroutine

  subroutine do_dump_fields_periodically(t)
    use file_utils, only: open_output_file, close_output_file
    use kt_grids, only: naky, ntheta0, aky, theta0, akx
    use theta_grid, only: theta, ntgrid
    use fields_arrays, only: phinew, aparnew, bparnew
    use constants, only: run_name_size
    use mp, only: proc0
    implicit none
    real, intent(in) :: t
    character(run_name_size) :: filename
    integer :: ik, it, ig, unit

    if (.not. proc0) return

    write (filename, "('dump.fields.t=',e13.6)") t
    call open_output_file(unit, '.'//filename)
    do ik = 1, naky
       do it = 1, ntheta0
          do ig = -ntgrid, ntgrid
             write (unit=unit, fmt="(20(1x,e12.5))") &
                  theta(ig), aky(ik), theta0(it,ik), &
                  phinew(ig,it,ik), aparnew(ig,it,ik), &
                  bparnew(ig,it,ik), t, akx(it)
          end do
          write (unit, "()")
       end do
    end do
    call close_output_file (unit)
  end subroutine do_dump_fields_periodically