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Transcript
of the experimental results and ID theory. These results demonstrate the predictive
capability of the charge injection model.
0.6
9 IeM Homogeneous
- * - Icl Homogeneous
0.5
0.4
0.3
0.3 -
4
.D
Case 1
Casel
Case 2
Case 2
-.
..
I.tC
s
.. ..
..
..
-0 .1.
2
4
6
8
10
12
.
-
-
IeM
- * - Ii
A-- I
- -.* -c1,,l
14
Applied Voltage in kV
Figure 4-20: Emitted and collected current for homogeneous boundary condition and
charge injection boundary condition cases: 1) Pref
10-4 Cm- 3 , Erf = 100 kV/cm,
3
2) pref =1-5 Cm- , Eref = 1kV/cm on coarse mesh, 3) pre=10-5 CM- 3, Eref
IkV/cmyl on fine mesh.
Electric field strength, charge density, and current density on the surface of the
emitter for the homogeneous, low sensitivity charge injection, and high sensitivity
charge injection boundary condition cases are shown in figure 4-21. The homogeneous
boundary condition results in constant current density.
The charge density varies
around the perimeter inversely to the electric field strength. The field strength from
the homogeneous boundary condition case is 20% lower than the critical value E..
This indicates that either Peek's law does not accurately predict the critical field
strength or the 2D model does not capture some 3D corona discharge effects.
The
surface condition parameter used in Peek's law to calculate the critical field strength
is m, = 1. A different choice of m, could result in a closer match to the experimental
results.
The high sensitivity charge injection case drives the electric field strength to within
5% of the critical value. Charge density at the surface of the emitter exhibits far more
variation around the circumference compared to the lower sensitivity charge injection
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