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GENIUS evaporation controller, CARRERA high-voltage power
supply and FPS filament power supply, with high-voltage power connector

• GENIUS evaporator control unit
• CARRERA high-voltage power supply
  (3 kW, 5 kW or 10 kW)
• FPS filament power supply

High Voltage Power Supplies HV:

The operation of any electron beam evaporator requires a well-matching set of power supplies and a control unit, in order to generate and guide the electron beam. The high-voltage power supply must deliver the electron-emission current at several kV to the cathode of the emitter assembly.

A high-current filament power supply FPS, floating at the high-voltage potential, is further needed to heat the electron-emitting filament. The control unit is responsible for all security issues, the beam positioning and power setting, thus basically providing the user-interface for the whole e-beam evaporation system. For all our e-beam evaporators, EBV, EBVV and EBVM, we offer the GENIUS evaporation controller together with a CARRERA high-voltage power supply and the matching filament power supply FPS.

This combination offers several benefits:

Rate Feedback Control

Compared to a simple radiation-heated effusion cell, the precise rate control of the molecular beam flux from an e-beam evaporator needs a little more effort.

Due to thermal fluctuations in the melt and the high power density at the e-beam focus, random short-term flux variations are usually observed. In addition, a change in the heat transfer properties from the evaporant to the water cooled crucible walls can cause flux changes at a constant e?beam power.To achieve a constant evaporation rate from an electron beam evaporator, a flux- or rate-feedback control often is desirable in MBE applications.This can be accomplished by different flux-measurement techniques, e.g. with a cross-beam mass spectrometer detecting the actual evaporant atoms from the source, with a quartz crystal balance or with optical detection methods.

The rate signal is given to a PID-feedback controller, which regulates the emission current of the electron beam to the desired setpoint value, thus achieving a constant beam-flux from the EBV. The GENIUS evaporation controller has for this purpose a built-in analogue input for remote control of the emission current. Hence, it can be easily integrated in such a feedback loop.An example of a feedback set-up with a crossbeam quadrupole mass spectrometer is shown in Fig. 109.If you wish to set up a feedback regulation with the EBV, please contact us for advice.

We can provide you with a complete feedback regulation system adapted and optimised to your growth environment, including flux measurement equipment and PID feedback controller. Please ask for a customised quotation for your application.

Scheme of a feedback set-up with QMA and PID-controller

Cables between power supplies and the EBV 200?100 are always an integral part of the power-supply-ensemble. The standard length of the high-voltage cable between the FPS and the evaporator on the vacuum system is 3 m. It can be extended to maximum admissible length of 5 m for this connection.The CE-conform high-voltage connector mates with the HV-feedthroughs on the EBV (M / V) flange (see Fig. 108).In contrast, the x-y beam deflection cable from the GENIUS controller to the EBV can be tailored to custom length (6m is standard).

High-voltage connector with 3m HV cable and x-y deflection connector

The high voltage power supply CARRERA is available with three different output power ranges: 3kW, 5kW and 10kW. For most molecular beam applications 3kW or 5kW are largely sufficient. However, the 10 kW version may be necessary for some materials. The GENIUS control unit and the FPS are always the same. We recommend the 5kW CARRERA as the most flexible yet affordable solution assuring to be prepared for possible higher power needs in future applications.

Dimensions

* clearance behind device needed for connectors and cabling

 LAST UPDATE: NOVEMBER, 2004

© 2003 Dr. Eberl MBE-Komponenten GmbH