def nb0(self):
        """
        On-axis beam density :math:`n_{b,0}`.
        """
        return self.N_e / (4*_np.sqrt(3) * _np.pi * self.sig_x * self.sig_y * self.sig_xi)
def nb0(self):
        """
        On-axis beam density :math:`n_{b,0}`.
        """
        return self.N_e / (4*_np.sqrt(3) * _np.pi * self.sig_x * self.sig_y * self.sig_xi)
def nb0 ( self ) : return self . N_e / ( 4 * _np . sqrt ( 3 ) * _np . pi * self . sig_x * self . sig_y * self . sig_xi )
On-axis beam density :math:`n_{b,0}`.
On - axis beam density : math : n_ { b 0 } .