• Local or Remote Control of Beam Energy, Filament Power and Emission Current
  • Integrated Floating Filament Supply
  • Active Bias System
  • RS-232 Control and Monitoring Interface
  • High Stability, Less Than 2.5 ppm

50 kV Electron Gun High Voltage Power Supply

Spellman’s precision Electron Gun Power Supply is designed to achieve extremely high stability and low ripple. The EGM50 incorporates an integral floating filament supply and and active bias. Full control via RS-232 interface reduces end-product development time and eases system integration. Safe, ground level local and remote control of beam energy, filament power and emission current provides optimum operational efficiency.

Typical applications:

  • Electron-Beam Lithography
  • Semiconductor Inspection
  • Scanning Electron Microscopes

CE Marking


(Ref. 128017-001 REV. F)

Input Voltage:


Input Current:

<1.1A @ 100Vac 

Input Frequency:

47 to 63Hz

Input Protection:

IEC inlet 3.15A “T” fuse

Temperature Range:

Operating: 20°C to 25°C

Storage: -10°C to 70°C

Operating Humidity:

10 to 70% RH

Connections and Cables:

9-pin “D” type: System Interlocks

25-pin “D” type: RS232

RJ485: Optional Ethernet

Optional HV Cable: 8m (XPVD-75-3Y) Hitachi

3-pin HV: 75kV DC Standard Federal Connector

Local Control:

Front panel push button for filament power and emission current increments Beam energy on and off

Remote Control:

Via an RS-232C for Beam Energy, Filament Power, and Active Bias


Digital monitoring via RS232C. Analog output monitoring provided via BNC connectors on the rear panel

Front Panel Monitor:

Display 1: Beam energy or bias voltage

Display 2: Emission current

Display 3: Filament power


2 x 3U 19” Rack Units


Control Module 10kg (22lbs.)

HV Module 40kg (68lbs.)

Regulatory Approvals:

Compliant to 2004/108/EC, The EMC Directive and 2006/95/EC, The Low Voltage Directive


Output Voltage:

-50kV fixed, adjustable ± 2% via remote control. (Other output voltages available upon request)

Output Current:

500µA maximum



Line Regulation:

<10ppm for a 10% line change at 50kV 500μA 

Load Regulation:

<10ppm for 100 to 500μA emission current change 



Warm Up Time:

5 hours for full stability

Ripple and Noise:


Overcurrent Protection:

Protected against overcurrent to 120% of the rated current. Unit will shutdown for over current condition greater than 100ms

Arc Protection:



Output Power:

10W max. (adjustable in 0.1W steps)

2A maximum current

8.4V maximum voltage


Constant with secondary side control

Line Regulation:

<10ppm for 10% line change 

Load Regulation:

<5% change in power from 4W to 7W (1Ω to 7Ω) 


<50ppm/12 hours/0.5°C after warm-up 

Warm Up:

<3 hours for full stability 

Ripple and Noise:

<0.1% (operating frequency)

<50ppm (10Hz to 3 kHz) 


+1.00V for 10W

100ppm Stability

0.5% accuracy


Voltage Range:

Low: -200 to -1100V ref to filament center tap

High: -200 to -2000V ref to filament center tap

Low or high range selected via rear panel switch

Temperature Coefficient:


Emission Control:

0 to 500µA adjustable in steps of 0.1µA

Emission Monitor:

+5V for 500µA output

100ppm stability

0.1% accuracy


Pin Signal Signal Parameters
1 PSU on Volt free contacts to indicate that there is
power on the unit
2 N/C No Connection
3 N/C No Connection
4 N/C No Connection
5 0V No Connection
6 Interlock/HV Enable Link to 0V to enable HV output
7 N/C No Connection
8 N/C No Connection
9 PSU on Volt free contacts to indicate that there is
power on the unit


Pin Signal Signal Parameters
1 N/C No Connection
2 TX PSU Transmit Data
3 RX PSU Receive Data
4 RTS Ready to Send
5 CTS Clear to Send
6 N/C No Connection
7 0V  
8 N/C No Connection
9 N/C +12Vdc up to 100mA, switchable
10 N/C No Connection
11 N/C No Connection
12 N/C No Connection
13 N/C No Connection
14 N/C No Connection
15 N/C No Connection
16 N/C No Connection
17 N/C No Connection
18 N/C No Connection
19 N/C No Connection
20 N/C No Connection
21 N/C No Connection
22 N/C No Connection
23 N/C No Connection
24 N/C No Connection
25 N/C No Connection

Tables & Diagrams



EGM High Voltage Power Supply (Image 1)


EGM High Voltage Power Supply (Image 2)

Note: All specifications are subject to change without notice. Please consult the PDF version of this datasheet for the most up-to-date revision.