Consider an electron beam of uniform circular cross-section witha diameter of 1 mm. The electrons are accelerated from the cathodeto the anode, which are separated by 1 m. The electrons aregenerated at the cathode and therefore have negligible velocity atthis position. The electrons accelerate at a rate of 108 ?/?2between the cathode and anode. The current density at the anode is104 ?/?2 .
Find the current density as a function of position between thecathode and anode.
