RF Generator Busbar Damping for Stable Plasma Power
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Solution Overview
Problem
RF generators for plasma applications face challenges in stabilizing DC power supply due to stray impedance, leading to transient voltage excursions and oscillations, which are typically addressed using electrolyte capacitors that require cooling and occupy significant space, making them unsuitable for high-power applications in compact housings.
Innovation Solution
The RF generator employs a damping network with ceramic capacitors and a metal busbar to reduce transient voltage excursions, using a PCB-based busbar with a damping network that includes capacitors and resistors to shape transients, allowing for efficient cooling and compact design, thereby increasing reliability and reducing the need for large electrolyte capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If electrolyte capacitors are used to suppress voltage fluctuations, then the stability of DC power is improved, but the device occupies significant space and requires additional cooling
Solution Approach 1:
The patent changes the capacitance value parameter from large (1000-2000 μF) to small (10-100 nF), enabling the use of ceramic capacitors instead of electrolyte capacitors. This parameter change resolves the contradiction by achieving voltage fluctuation suppression with much smaller components that do not require additional cooling
Solution Approach 2:
The patent introduces a damping network as an intermediary circuit between the power supply and the PA, consisting of small ceramic capacitors (10-100 nF) combined with resistors. This damping network acts as a mediator to suppress voltage fluctuations without requiring large electrolyte capacitors, thereby reducing space occupation while maintaining DC power stability
2Stability of the object's composition
If electrolyte capacitors are used to suppress voltage fluctuations, then the stability of DC power is improved, but the device complexity increases due to cooling requirements
Solution Approach 1:
The patent changes the capacitance parameter to use small ceramic capacitors (10-100 nF) instead of large electrolyte capacitors, which eliminates the need for additional air cooling systems. This resolves the contradiction by maintaining DC power stability while reducing device complexity
Solution Approach 2:
The patent uses small, inexpensive ceramic capacitors with long operational life instead of expensive electrolyte capacitors that require cooling. The ceramic capacitors are more reliable and do not have the same thermal limitations, simplifying the overall system
3Stability of the object's composition
If large capacitance is used to suppress voltage fluctuations, then the stability of DC power is improved, but the housing width must be increased to 19-inch
Solution Approach 1:
The patent changes the capacitance parameter from large (1000-2000 μF) to small (10-100 nF), enabling compact housing design. The small ceramic capacitors can be mounted on the cooling plate without requiring additional spacing, allowing the housing width to remain at 19/2-inch (241.3 mm) instead of requiring full 19-inch width
4Productivity
If fast pulse-mode operation is implemented, then the productivity is improved, but transient voltage excursions and oscillations occur due to stray impedance
Solution Approach 1:
The patent implements preliminary action by placing damping networks (small ceramic capacitors of 10-100 nF with resistors) at strategic locations in the circuit before voltage fluctuations can propagate. This allows fast pulse-mode operation while preventing transient voltage excursions and oscillations caused by stray impedance
Solution Approach 2:
The damping network acts as an intermediary that decouples the effects of fast switching from the DC power supply. The small ceramic capacitors in the damping network respond to high-frequency transients without affecting the overall DC stability, enabling fast pulse operation with maintained voltage stability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides a stable and reliable RF generator operation with reduced over- and undershoots, increased reliability, and a compact design that fits within a 19/2-inch housing, while avoiding the limitations of electrolyte capacitors, such as cooling requirements and space constraints.
Implementation Method 1
The busbar comprises a damping network comprising a plurality of capacitors connected between ground and the busbar and configured to shape transients on V busbar
Implementation Method 2
the cooling element may be built as cold plate including one or more channels or pipes through which a coolant can flow in order to cool the cold plate
Implementation Method 3
the cooling element may be built as cold plate including one or more channels or pipes through which a coolant can flow in order to cool the cold plate
Data Source
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AI summary
Radiofrequency, RF, generator, in particular for a plasma application, comprising: at least one cooling element having an upper surface and a lower surface; at least one DC power supply; at least one power stage to amplify an RF signal and connected to the upper surface of the at least one cooling element, wherein the power stage comprises one or more power amplifiers; a driver to supply the power amplifier of the at least one power stage and connected to the upper surface of the at least one cooling element; wherein the at least one DC power supply is connected by a busbar with the power amplifier and the driver, wherein a DC voltage Vbusbar is supplied to the power amplifier and the driver via the busbar; and wherein the busbar comprises a damping network comprising a plurality of capacitors connected between ground and the busbar and configured to shape transients on Vbusbar.