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Krytron

A krytron is a four element (cathode, grid, anode, and keep alive) gas filled cold cathode switching tube. Example: KN22.

The control grid in these devices actually encloses the anode with a small opening at the top. Conduction occurs through this hole. The gas in the tube provides ions to neutralise the space charge allowing a high current to be obtained at a lower voltage than otherwise possible.

Krytrons contain a small amount of radioactive Ni-63 which is a beta emitter. This aids the initial glow discharge between the cathode and the keep alive electrode.

Krytron schematicKN22 connections

 

Type
Anode voltage (kVDC)
Trigger volts (V)
Current (A)
Pulse
Min
Typical
Max
Max peak
Typical peak
Keep alive (µA)
Duration (µS)
Delay time (µS)
Jitter (µS)
Repetition (PPM)
Life (x 107)
KN-2
0.3
2.0
4.0
200
500
40
50
5
0.20
0.02
61
1
KN-4
0.4
1.2
5.0
250
2500
270
150
10
0.30
0.03
1
0.0025
KN-6
0.7
2.6
5.0
250
3000
715
50
10
0.25
0.03
1
0.0035
KN-6B
0.7
2.8
8.0
250
3000
715
50
10
0.50
0.05
1
0.0035
KN-9
0.3
1.5
4.0
200
500
1
50
5
0.20
0.02
24x103
1.5
0.4
4.0
5.0
750
100
80
300
0.04
0.04
0.005
3x103
2

This file was last modified 23:18:54, Friday November 02, 2012