The aim of this work is to obtain a modified Bohm equation with new diffusion factor C and as expected to be differing from Bohm's factor (1/16). This is done by constructing a program using computer simulation; this factor was proposed by Spitzer (1960), and modified by Sanduk (1997). Computer simulation experiment program for plasma has been constructed to satisfy a plasma confinement system in two dimension (X,Y plane) as a result of applying a magnetic field normal to the plane of the plasma and has variable curvature . In a curved magnetic field, a resulting centrifugal force with acceleration (g) acts in the plane due to the particle motion along the curved lines of force which affect reversibly to the plasma density gradient Vn, this kind of instability generation is called flute mode instability. The size of the constructed system was proposed to be (64x64)λ, D, XD, where XD is Debye length of system, while the unit time was chosen to τ = _²π , where ω is the instability frequency . The perturbed electric field Ề has been determined and the perturbed values as a result of applying magnetic field curvature yield to calculating of the drift velocity VExB, which is responsible to the losses of plasma near the wall side of the system. This study demonstrate clearly the fluctuations growth rate which start near the wall of the system with low amplitude and extended towards the source as the time proceeds. This is demonstrated to all plasma parameters ( ń , φ Ề V). Bohm diffusion coefficient for plasma has been calculated by many methods. The well-known method of calculation is that given by Spitzer, which depends on the measurement of the perturbed electric field. The C factor was calculated by different manners:- 1- From the modified equation by Sanduk (1997), that depends on the growth rate calculation; this quantity is estimated theoretically and experimentally. 2- Using Dupree equation and Spitzer relation the growth rate is calculated and then used to determine the C factor. Our computational simulation experiment results yield an instability factor, which is less than given by Bohm i.e. The C factor dedicated by this work shows a good agreement with those given by previous authors.The C factor dedicated by this work shows a good agreement with those given by previous authors