英国YPS电镜灯丝YP74，YPS场发射灯丝YP74，

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

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