General Cabling Considerations For Plasma/Load - Advanced Energy VarioMatch Match Network VM 1000 Platform User Manual

Cable Requirements

GENERAL CABLING CONSIDERATIONS FOR PLASMA/LOAD

The main objective of an RF delivery system is to provide as much of the generator's
output power to the load as possible. However, losses occur in the coaxial cable, the
match network, and in the lead between the match network and load. These losses
should be kept as low as possible.
Guidelines to Minimize Losses
Use the following guidelines to minimize losses:
• Keep RF cabling between matching network and load as short as possible.
• Ensure proper shielding of all RF
• Ensure a proper RF return path (ground). Remember that RF can only run on the
surface, but
• All RF conductive parts should consist of silver plated copper, electrolytic copper,
aluminium, or stainless steel.
• Do not use regular steel because it is a bad RF conductor. It will cause high losses
and eventually burn away.
Guidelines for PLASMA/LOAD Cables and Connectors
The proper connection of the VarioMatch match network to the load influences
operation of the whole RF system. The following is important information for
connecting to PLASMA/LOAD.
There will be a high RF current flowing between the V arioMatch match network and
the load. The RF output (PLASMA/LOAD) is much higher than RF input (RF­
GENERA TOR). High currents are common because the real part of a load
impedance is typically between 1 Q and 10
even at low RF power levels.
Due to skin effects, the RF current will flow only on the surf ace of the conductor,
reaching a depth of only 10 micrometers to 20
conductor material and the frequency. To reduce the conductive losses as well
unwanted voltages drops across the lead, always try to optimize the surface area of a
lead.
The large RF current flowing through the lead to the load will cause losses in power as
well as RF radiation. For optimum
lead surface area. If you don't use a coaxial cable as the PLASMA/LOAD connection
(coaxial cable should not be used at power levels exceeding approximately 1.5 kW),
you must ensure adequate RF shielding of the connection to prevent RF radiation
which can cause malfunctions in nearby instrumentation and electronic equipment.
57020080-00D
AE VarioMatch
TM
leads.
not through material.
n.
results, minimize the lead length and maximize the
Installation, Setup, and Operation
Match Network, VM 1000/1500 Platform
This results in a relatively high current
micrometers, depending on the
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