Electrostatic deflector
Project details
- different harmonic components computed from distribution of electrode potentials, from which the excitation of deflector is evaluated.
- There are eight electrodes, axis x goes through the electrode, 0.2 deg gaps, voltages 1 and 0.70111 and 0 in the first quadrant
Geometry and potential
Field accuracy
To estimate the accuracy of computation, the same coarse mesh was used, but q=1.025, and 10 and 20 points of fine mesh under the deflector. The comparison follows from the plot file below.
Axial field function
Test of the shape of deflection field for higher multipole components. For this the excitation was given numerically as 10m, where m is the multipole component (10 is the radius of the deflector). The result is shown on the next plot.
Optical properties
Finally, we estimate the optical properties of the deflector. Because there is no lens in the project, we can either do ray tracing, or we can calculate the optical properties as deflection slope and aberration coefficients.
Deflected trajectory
Aberrations
Trace file: D:\TU-EOD1\testuj\edefl\aberrations.EODtrc
Integration method Runge-Kutta Fehlberg 4-5 order
Max. step size = 0.10000000 mm
Axial fields interpolation: cubic spline
Relativistic correction: off
Particle electron, charge -1e
-----------------------------------------------
Aberrations calculation results
-----------------------------------------------
Fields used for tracing
Fields:
1 .\dem1emd-20-1357.EODinp
Electrostatic deflector - field
main deflector
Field is symmetrical
Interpolation Cubic spline
Field zmin (original) -60.000000000 mm
Field zmax (original) 60.0000000000 mm
Field magnitude 1.00000000000
Field z shift 0.00000000000 mm
Field rotation 0.00000000000 deg
# of points 126
Field maximum 0.99962 V/mm^0
Maximum z [mm] 0.00000
Field width [mm] 50.51249
----------------------------------------------------
Particle properties:
Object position zo= -6.0000000E+01 mm
Energy= 1.0000000E+04 eV
U= 1.0000000E+04 eV
Delta Energy= 1.0000000E+00 eV
Aber. for aperture= 5.0000000E-03 rad
Aber. for obj. height= 1.0000000E-03 mm
Deflection X= 1.0000000E+00 mm
Y= 1.0000000E+00 mm
Image # 0 (asymptotic), image # 1 not found!
Image position zi= -6.0000000E+01 mm
Beam rotation= 0.0000000E+00 rad
0.0000000E+00 deg
Image magnification= 1.0000000E+00 times
Aberration coefficients related to image
-------------- Main deflection -----------------
Deflection x= 1.6023159E-01 mm
y= 0.0000000E+00 mm
total= 1.6023159E-01 mm
Angle= 0.0000000E+00 rad
Angle= 0.0000000E+00 deg
Slope x'= -2.6705265E-03
y'= 0.0000000E+00 mm
Main deflection aberration coefficients
Aberration coefficient | Error in micrometers
---------------------------------------------------------------------------------------
coma length: 5.0000E-01, 0.0000E+00 | 1.8750E-02, 6.2500E-03 um
field curvature: 6.4269E-03 1/mm | 6.4269E-02 um
astigmatism: 3.8057E-03, 0.0000E+00 1/mm | 0.0000E+00, 3.8057E-02 um
distortion: 4.6756E-05, 0.0000E+00 1/mm^2 | 9.3511E-02, 9.3511E-02 um
chromatic: -1.0000E+00, 0.0000E+00 | -1.0000E-01, -1.0000E-01 um
landing error: -1.6667E-02, 0.0000E+00 rad/mm | -9.5493E-01, -9.5493E-01 deg
----- Total aberration (geom. and. chrom) 2.0847E-01 um
Mixed aberration coefficients for finite object
kappa F= 0.0000E+00, 0.0000E+00 A= -8.3333E-03, 0.0000E+00 1/mm
dist. D1= 0.0000E+00, 0.0000E+00 D2= 0.0000E+00, 0.0000E+00 1/mm^2
D3= 3.2531E-04, 0.0000E+00 D4= 1.9190E-04, 0.0000E+00 1/mm^2
|
Examples 
