3: Thermionic Emission

Example number 3.1, Page number 67

In [1]:
#importing modules
import math
from __future__ import division

#Variable declaration
S=2*10**-6;      #tungsten filament(m**2)
T=2000;      #temperature(K)
A=60.2*10**4;   #value of A(amp/m**2 K)     
b=52400;       #value of b 
e=1.6*10**-19;   #electron charge(c)

#Calculation
I=A*S*(T**2)*(math.exp(-(b/T)));   #electronic emission current(amp)
J=A*(T**2)*(math.exp(-b/T));      #emission current density(A/m**2)
no=J/e;          #no. of electrons emitted per unit area per sec(per m**2 sec)

#Result
print "maximum obtainable electronic emission current is",round(I*10**6,3),"micro amp"
print "emission current density is",round(J,5),"A/m**2"
print "no. of electrons emitted per unit area per sec is",round(no/10**19,3),"*10**19 per m**2 sec"

maximum obtainable electronic emission current is 20.145 micro amp
emission current density is 10.07259 A/m**2
no. of electrons emitted per unit area per sec is 6.295 *10**19 per m**2 sec

Example number 3.2, Page number 67

In [2]:
#importing modules
import math
from __future__ import division

#Variable declaration
Ip1=20;       #plate current(mA)
Ip2=30;       #changed plate current(mA) 
Vp1=80;       #plate voltage(V)

#Calculation
#Ip=K*(Vp^(3/2))
Vp2=((((Vp1)**(3/2))*Ip2)/Ip1)**(2/3);       #changed plate voltage(V)

#Result
print "plate voltage for 30mA current is",round(Vp2,2),"V"

plate voltage for 30mA current is 104.83 V