Space Charge Limited Emission

Home

        Calculate:   Current      Output Format        Notes

Definition:                           

Equation

Parameters

Diagram

Calculate Current in Cylindrical SC Limited Diode:        top

Parameter

Value

Units

Special Values

Inputs:

 V (voltage)
d (gap length)  
A (cathode area)
         

Outputs:

ISCL(current)

Z (impedance)

 

Output Format:                                                        top

Select Format: Scientific Engineering Fixed

 

Notes:                                                                       top

Source:  NRL Plasma Formulary
This is for non-relativistic electron emission and transport in vacuum.
Assumes no initial electron velocity. Assumes no ions (ions generally increase electron current 100% (half impedance), but are a small fraction of total current) Effective area can be spreading of the electron source. According to Bruce Weber (NRL), this equation only works up to about 500kV.  Above this, replace the 2.34 with 2.00 in the coefficient and the 3/2 with 4/3 in the exponent for a better fit.  

 

Copyright ©2002  Raymond J. Allen