Matching Network: Impedance 10kW to 50kW Manual and Automatic

Product Description for MMN-AMN High Power Matching Network

Coaxial Power Systems Ltd manufacture two styles of impedance matching network to link the load to the RF generator. The purpose of the network is to adjust the input impedance of the load to 50 Ohms so that maximum power is transferred from the generator, whose output impedance is 50 Ohms, to the load. The network must be installed as close a possible to the load. The best possible position, in a plasma application for example, would be to mount the network directly on the vacuum chamber with a direct connection to the electrode or magnetron.

Coaxial Power Systems Ltd. manufacture two types of network - Manual and Automatic

Manual

The manual matching network consists of two adjustable vacuum capacitors and a fixed inductor, which are usually arranged as an "L" network. Other arrangements such as "Pi" and "T" are also available. Cranked knobs with built in turns counters are used to adjust the capacitors for minimum reflected power as displayed on the generator reflected power meter. When the reflected power is zero, the system is "tuned" and all of the power output of the generator is being fed to the load. The inductor is water cooled. For high powers (>25kW ) the vacuum capacitors are also water-cooled.

Automatic

The automatic matching network is similar to the manual version except that servomotors drive the capacitors. .At the input of the network, a phase and magnitude detector determines the position of the capacitors. This information is transferred to the separate controller. The controller then drives the servomotors to the positions, which give zero, or minimum reflected power.

The controller is 1/2 rack, 4U high and is usually fitted in the same enclosure as the generator.

The position of each variable capacitor is shown on a 3 1/2 digit LED meter. Automatic or Manual mode is switch selectable - in manual mode the servomotors are controlled by spring loaded switches.

The start position of the capacitors can be individually adjusted. When RF power is detected, the capacitors automatically adjust for minimum reflected power. When the RF is turned off, the motors drive the capacitors back to heir original position. The start positions are adjusted using potentiometers accessible via the controller front panel

Option: Model DCP-1 : Dark Space Bias Voltage Measurement and Control (Automatic MN only)

A probe, installed inside the network, measures the d.c voltage (0 to 1999V) developed across the dark space in plasma applications such as sputtering and reactive ion etching. The voltage is converted to a 0 to 5V signal which can be fed back to the generator control system. The voltage is displayed on the loading capacitor position meter. Includes all necessary cables to link to any generator in the low power range manufactured by Coaxial Power Systems Ltd.

Technical Specifications for MMN-AMN High Power Matching Network

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