CUSTOM DEVELOPMENT & consulting SERVICE
You don't find the solution that fits your need? We can make it.
Here are some examples of custom developments we made.
Impedance matching network for a large area VHF CCP reactor (LPP Laboratory, France)
This customer needed a custom manual matching network for a large area capacitively coupled plasmas (CCP). The matching network should be able to perform the impedance matching up to 600W at four different RF frequencies: 13.56, 40.68, 60 and 81.36MHz.
The input impedance of the reactor (without discharge) was measured with a Vector Network Analyzer between 1 and 100MHz in order to design this optimized matching network.
The input and output RF ports, cooling air inlet and outlet were positioned to fit the customer needs. The series "tune"
inductor can be easily accessed at the back to modify its value before changing the excitation frequency.
Multi-frequency Impedance Matching Network (LPICM Laboratory, France)
Driving radio-frequency capacitively coupled plasmas (CCP) by (non-sinusoidal) tailored voltage waveforms has been shown to allow considerable control over various plasma properties for surface processing applications.
A tailored voltage waveform (such as a "peak" waveform illustrated on the right) is synthesized by exciting a single electrode with a group of harmonics. The impedance matching becomes therefore more complicated. Until now, this problem has been handled in research laboratories by using an oversized amplifier that can tolerate almost full power reflection without any impedance matching network, thus limiting the applicability of this technique to very small/low power laboratory systems (<50W).
To overcome this limitation a novel matching network has been invented by our customer. We built for the LPICM laboratory at Ecole Polytechnique in France two prototypes of a matching network (300W) able to match a CCP reactor simultaneously at 3 excitation frequencies (13.56, 27.12 and 40.68MHz). Two different prototypes have been built to equip two different CCP reactors.
A multi-frequency matching network is based on a network of 6 LC resonant circuits. The inductors are fixed air core copper coils, and the capacitors are variable vacuum capacitors. The 6 capacitors can be manually tuned from the front panel. A great attention was paid to the design and the placement of the various components to minimize the stray impedances and losses.
The effectiveness of such matching network was demonstrated experimentally (see reference below) on an Ar plasma excited by a three-frequency voltage waveform with a fundamental frequency of 13.56 MHz. Under the plasma conditions studied, the power coupling efficiency was increased from less than 40% (without impedance matching) to between 80% and 99% for the different exciting frequencies.
Source: Wang et al. Journal of Vacuum Science & Technology A 37, 021303 (2019) https://doi.org/10.1116/1.5056205
Very High Power Voltage-Current Probe (Institute of Plasma Physics, China)
The Institute of Plasma Physics (ASIPP) in China contacted us to help them reduce the reflected power at the input of a very high power (50kW) impedance matching network (at 27.12 and 40.68MHz) used to power two heating antennas of the EAST tokamak.
We designed and built a custom voltage-current probe to be installed into a 3-1/8" EIA rigid coaxial line at the matching network output. The maximum voltage and current amplitudes to be measured at 27.12 and 40.68MHz are 10kV RMS and 100A RMS.
A 3D drawing of the designed probe is shown on the left. After validation by the customer we have built, calibrated and shipped the probe.
A photography of the probe integrated in the customer's system is shown below.
In addition to the design and manufacturing of the probe we provided 10 days of consulting service to help the customer interpret the RF measurements and optimize its matching network.
The customer was able to measure the load impedance and modify the design of the matching network to achieve a good impedance matching.
Atmospheric Pressure 13.56MHz Micro-plasma Jet Generation System (Chile)
A researcher in Chile contacted us because he wanted to process agricultural seeds with an atmospheric micro-plasma jet excited at 13.56MHz. The goal is to increase the germination rate as reported in some recent scientific articles.
A micro-plasma jet is a radio-frequency capacitively coupled plasma (CCP) generated in a gas flow chanelled between two linear electrodes.
That researcher had a limited budget. Despite that constraint we were able to design and manufacture a full generation system integrated into a small 19-inch rack frame. This turn-key system consists of:
- RF signal generator (adjustable excitation frequency);
- solid-state RF switch (to pulse/modulate the power up to 1kHz);
- RF power amplifier (30W);
- wattmeter (to measure the power delivered by the amplifier);
- manual impedance matching network;
- 50 Ohms dummy load (for testing purpose);
- coaxial cable terminated by the micro-plasma source.
We designed the system to be modular and easily repairable by the customer due to the remoteness of Chile.
The micro-plasma jet shown on the right was generated within a Neon gas flow at 25W.
