A particle of charge q and mass m is projected from origin with an initial velocity $\vec{v}=\left(\frac{v_0}{\sqrt{2}} \hat{x}+\frac{v_0}{\sqrt{2}} \hat{y}\right)$. There exists a uniform magnetic field $\vec{B}=B_0 \hat{z}$ and a space varying electric field $\vec{E}=E_{\mathrm{o}} \mathrm{e}^{-\lambda x} \hat{x}$ within the region $0 \leq \mathrm{x} \leq \mathrm{L}$. After travelling a distance such that x -coordinate has changed from $\mathrm{x}=0$ to $\mathrm{x}=\mathrm{L}$, the change in the kinetic energy is $\_\_\_\_$ .