Compact SMPS based Sputter Ion Pump Power Supply

Conventional Sputter ion pump power supplies tend to be heavy and bulky as they operate on the mains frequency viz. 50Hz. Our design is based on the proven leakage inductance high frequency transformer followed by a rectifier cum voltage multiplier. This power supply is based on a half bridge dc to dc converter operating at 20kHz resulting in a drastic size reduction of around 75% over conventional power supplies. This in turn results in a compact vacuum system with a smaller footprint. Our compact switched mode triode sputter ion pump power supply is rated for an open circuit voltage in the range of -6kV to -7kV with a short circuit current rating of 200mA. This supply can power triode sputter ion pumps of capacities up to 140 liters / second. A microcontroller circuit is used to display the various parameters, implement the Trip logic and provide a PC interface.

Sputter ion pumps find extensive use in high vacuum systems where a “clean” vacuum is desired. In contrast to other common UHV pumps, such as turbo molecular pumps and diffusion pumps, ion pumps have no moving parts and use no oil. They are therefore clean, need little maintenance, and produce no vibrations.

The compact switched mode triode sputter ion pump power supply made in BARC is based on a half bridge dc to dc converter operating at 20kHz resulting in a drastic size reduction of around 75% over conventional mains frequency operated ion pump power supplies.

A direct mains operated half bridge chopper feeds power to a ferrite core leakage inductance transformer, the output of which is boosted by a rectifier cum voltage doubler to generate a voltage in the range of -6kV to -7kV. A microcontroller based circuit is used to display the various parameters, implement the Trip logic and provide a PC interface.

1.	Output voltage	: -6 to -7kV @ open circuit
2.	Output current	: 200mA @ short circuit
3.	Type	: Switch Mode Power Supply
4.	Processor	: NXP make P89V51RD2FA
5.	Display	: 7 segment Digital display 2 digits for mantissa & 3 digits for exponent
	Selectable display of	a) Voltage: 0 – 10kV FS b) Current: 0 – 200 mA in 5 decade ranges c) Pressure:10^-4 to 10^-9 Torr d)Pressure:10^-4 to 10^-9 mbar
6.	Membrane keypad	: 4 x 1 Keys RESET, H V ON/OFF Scroll up and Scroll Down
7.	Protection	: Overpressure Trip set at 1 X 10^-3 T 30 Min Timer Based Trip set at 1 X10^-4 Torr
8.	Input	: 230 VAC ± 10%, 50Hz, 1Φ
9.	Trip interlock	: A potential free contact preset to 5 X 10^-5 Torr. Contact rating 230V, 1 Amp
10.	H. V. Termination	: Lemo make 2 Pin HV connector
11.	Serial Interface	: RS 232 Modbus RTU protocol
12.	Output Cable	:: Shielded 10 kV Teflon insulated HV cable

Facilities and manpower requirement for commercial production, calibration & maintenance

Special Instruments Required :

Voltage (0 to -10V) & Current Source( 200ma to 1 microamp) for testing Digital display card
High Voltage probe up to 15 kV Motwani make
SMD soldering station (WMD-3, Weller make.)
Variac
Isolation transformer
Digital Multimeter
Dual Channel Oscilloscope

Manpower Requirements:

Technician level for assembly &preliminary testing
Technician level for mechanical work
Electrical/electronics engineer (degree/diploma level) for final testing