Xmpl3d25, 25th 'example' data file for CPO3D

CRT electron gun, rectangular grid


A tetrode design, as specified by J Hasker, IEEE Transactions on Electron Devices, Vol ED-18 (Number 9), 703-712 (1971).


The file was written when the memory and speed of PC's was much more limited than at present, so the available number of segments was small and the requested inaccuracies were fairly high to give a quick demonstration.


A grid at -145 V with a rectangular hole of 0.1125*0.35 mm is followed by an anode at 1000 V with a circular opening of radius 0.2 mm, which is followed by a plate at 2500 V.


421 segments are used in the present demonstration, and 27 cathode segments.


The 'ray space charge tube' method of assigning space charge is used.

The 'phase space' option is also used.


4 iterations are called, giving the following values of the total current (before symmetry reflections):

-9.436 mA, -7.689 mA, -7.471 mA, -7.935 mA, -7.448 mA

After several further iterations this converges to -8.89 mA.


The 'phase space' option gives the following approximate range of coordinate and velocity phase space and z position of minimum of coordinate phase space, for x and then y direction:

3.14E-03 6.86E+06 -3.5449E-01

7.16E-04 4.58E+07 7.6218E-01

In other words the focus or line of least confusion effectively has a length of approximately 3 micrometres in the x direction, at z = -0.35, and a length of approximately 0.7 micrometres in the y direction, at z = 0.76.


The focussing in the horizontal (that is, x) direction seems to be weaker than given by Hasker, and that in the vertical direction looks stronger. The aberrations seem to be larger than given by Hasker.