英国YPS电镜灯丝YP74，YPS场发射灯丝YP74，

英国YPS电镜灯丝YP74，YPS场发射灯丝YP74总代理

	YP74-A
Applied / OPAL			YPS-M20-A
FEI (pre 2002)	YP74-F
FEI		YP84-F
Hitachi (TFE) SEM	YP74-H
Hitachi (TFE) CDSEM	YP74-C
JEOL (TFE)	YP74-J
LEO (Gemini)	YP74-L
PHI	YP74-P
Riber	YP74-R
Tescan		YP84-T
ZEISS (Gemini)	YP74-Z

Electron Source Performance Comparison:

Emitter Type	Thermionic	Thermionic	Schottky FE	Cold FE
Cathode material	W	LaB6	ZrO/W (100)	W(310)
Operating temperature [K]	2,800	1,900	1,800	300
Cathode radius [nm]	60,000	10,000	< 1,000	< 100
Effective source radius [nm]	>15,000	>5,000	~15 (*)	~2.5(*)
Emission current density [A/cm2]	3	30	5,300	17,000
Total emission current [μA]	200	80	100-500	5-10
Normalized brightness [A/cm2.sr.kV]	1 x 104	1 x 105	1 x 107	2 x 107
Maximum probe current [nA]	1000	Up to 10,000	Up to 1000	~2-5
Energy spread @ cathode [eV]	>0.59	>0.50	0.5-0.8	>0.23
Energy spread @ gun exit [eV]	1.5 - 2.5	1.3 - 2.5	0.5 - 0.8	0.3 - 0.7
Beam noise [%]	1	1	1	5 - 10
Emission current drift [%/h]	0.1	0.2	< 0.5	5
Operating vacuum mbar	< 1 x 10-5	< 1 x 10-6	< 1 x 10-9	< 1 x 10-10
Typical Cathode life [h]	100	> 1000	> 5000	> 2000
Cathode regeneration	not required	not required	not required	every 6 to 8 hours
Sensitivity to external influence	Minimal	minimal	low	high