Newton’s 2nd law states that Force is equal to the product of mass (m) and acceleration (a):
 F = m a ---> 1
 While in magnetic forces, force can also be expressed as:
 F = q v B ---> 2
 where,
 q = total charge 
 v = velocity = 45 cm / s = 0.45 m / s
 B = the magnetic field = 85 T
 First we solve for the total charge, q:
 q = 3.8 × 10^-23 g (1 mol / 23 g) (6.022 × 10^23 electrons / mol) (1.602 × 10^-19 C / electron)
 q = 1.594 × 10^-19 C
  
 We equate equations 1 and 2 then solve for acceleration a:
 m a = q v B
 a = q v B / m
 a = [1.594 × 10^-19 C * 0.45 m / s * 85 T] / 3.8 × 10-26 kg
 a = 160,437,862.2 m/s^2
  
 Therefore the maximum acceleration of Na ions is about 160 × 10^6 m/s^2.