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This paper describes design and implementation of highly efficient, low cost 13.56 MHz, 1.5kW RF source for ICP-AES. The design is based on current mode class-D power amplifier built using push-pull hybrid DRF1300. Prototype power amplifier achieves drain efficiency of 90% for power output above 1kW. Design shows that CMCD can achieve better effici...
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The article presents a new design of a CW RF high average current superconducting injector cavity. This design allows recovering energy in the injector, improving beam parameters and energy efficiency, reducing injector size, cost and avoiding high average power coupler problem.
Citations
... All of these results suggest that the preliminary experiment on the low-pressure Ar-O2 plasma generated by low-frequency AC power supply is worth studying and expending for the low temperature plasma fields in the future. High frequency [20,21] Low frequency up to 10kHz ...
We report a preliminary exploration on the low-pressure Ar-O2 plasma generated by low-frequency alternating current (AC) power supply in the low-temperature Plasma Experimental Power Supply (CTP-2000S) for the first time. The electron density 〖(n〗_e), the electron temperature 〖(T〗_e) and the electron energy distribution function (EEDF) are measured by the single Langmuir probe in this experiment. Experimental results show that the ne increases with gas pressure rising, while the ne decreases with the oxygen concentrations rising. And, a plasma density peak is also observed with the AC power supply increase. A comparison between this work and the previous results by RF source suggests that the low-frequency AC power supply may be very fruitful exploration to generate the low-pressure plasma.
... Class-D power amplifiers (Class-D PA) [26,27] are switching amplifiers that can provide 100% efficiency under ideal conditions, but the parasitic capacitance and on-resistance in the crystal switch reduce the actual efficiency. The current mode Class-D amplifier (CMCD) in [28] proposed zero-voltage switching (ZVS) to improve efficiency. This type of amplifier can take advantage of the drain capacitance of the circuit that loads the output so that it can be used in high-frequency circuits. ...
When it is necessary to detect various physiological signals of the human body, clothing embroidered with near-field effect patterns can be used as a long-term power supply medium to supply power to long-distance transmitters and receivers to form a wireless power supply system. The proposed system uses an optimized parallel circuit to achieve a power transfer efficiency of more than five times higher than that of the existing series circuit. The power transfer efficiency of simultaneously supplying energy to multiple sensors is increased higher than five times and even more when only one sensor is coupled. When powering eight sensors at the same time, the power transmission efficiency can reach 25.1%. Even when eight sensors powered by the coupled textile coils are reduced to one, the power transfer efficiency of the whole system can reach 13.21%. Additionally, the proposed system is also applicable when the number of sensors ranges from 2 to 12.
... However, typical transistor structure, in comparison to vacuum tubes, has inherently more pronounced parasitic parameters, mainly parasitic capacitances, which complicates the usage of transistors in RF generation. A traditional solution to this problem is to utilize specialized RF transistor assemblies [2], which are optimized to reduce the parasitic capacitances and inductances, and hence allow such an assembly to operate efficiently on RF frequencies. Of course, the employment of such assemblies significantly increases the cost of an RF generator. ...
... The supply voltage VS for the generator was chosen to be 48 V. Considering that IRFB4020 device can handle 200 V of drain source voltage, and that the LC Tank of CMCD circuit provides a voltage rise of π units [2], the supply voltage must be about 4 times lower than 200 V, leaving a safety margin. A standard value of 48 V was chosen. ...
Radio frequency (RF) energy is widely used in many technological processes. One of the main components of a typical RF system is RF generator, which supplies powerful RF oscillations to the load. Transistor–based generators have many advantages, but usually utilize specialized RF transistor assemblies, which significantly increases the cost of the RF generator. In this study it was shown that a powerful high efficiency RF generator can be built using cheap non–specialized MOSFETs. The test generator utilizing IRFB4020 MOSFETs was built using Current Mode Class D circuit, which allowed the generator to achieve an efficiency of 89% at an output power of 200 W supplied to a 50–ohm load.
... This concept is further refined in Class-E where a specially designed output network enforces that no current is flowing through the device when the voltage across it is high and no voltage is present when the device is passing large current, resulting in minimising ohmic losses [44]. A a result, the efficiency is the highest achievable, approaching 100 % in carefully designed circuits such as those described in [45][46][47][48]. ...
The popularity of the cubesat form factor has increased dramatically in the last few years, resulting in unprecedented access to space by smaller or medium sized organisations, universities and even smaller countries that could not afford such access in the past. However, the vast majority of the cubesats currently in orbit do not have a propulsion system. Such a system is invaluable as it can extend the satellite's time in space, assist with space debris avoidance manoeuvres, coordinate constellation orbits and facilitate a timely and controlled re-entry at the end of the mission. Various satellite propulsion methods have been developed and tested successfully in space over the past 50~years but it is not always possible to scale down a thruster to match the strict requirements of cost, power, size and so on, set by the cubesat platform. The objective of this thesis is to explore a number of options that, directly or indirectly, can help with the development of cubesat thrusters. The presented work includes a cost efficient method of measuring the performance of a cubesat thruster in the lab, using a load cell on a hanging pendulum thrust balance. The method shows good performance in comparison with the most expensive displacement measurement method, normally achieved by a laser interferometer. The thesis continues with the enhancement of the Pocket Rocket, an existing cubesat electrothermal RF thruster. The changes introduced are centred around a change from a capacitively coupled plasma system to an inductive one. These changes result in a more compact and efficient RF matching system which improves the overall efficiency of the thruster system, which is an important improvement for power-constrained cubesats. The new Inductive Pocket Rocket is placed in the Wombat space simulation chamber and a set of direct thrust measurements are made, showing the increase in thrust of up to 50%, then the plasma is ignited. Continuing on that theme, the thesis presents a very efficient RF source produced in collaboration with the Stanford Power Lab. It is based on the Class-E amplifier topology, which operates the power semiconductor at the two extremes - fully conducting to fully cut off, spending little time in the linear, lossy region of the transfer curve. This RF source, matched with a suitable DC power supply, exhibits electrical efficiency of over 91% resulting not only in better use of the limited power resources on-board the cubesat, but also less waste heat. The thesis continues with exploring an alternative propellant, naphthalene. Naphthalene sublimates at relatively low temperatures, producing enough vapour pressure to sustain the operation of a cold gas thruster. Cold gas thrusters generally have lower performance compared to other types of thruster systems for satellites but have the engineering advantage of simplicity. To that, naphthalene adds the advantage of having a propellant that is stored in solid state, resulting in negligible propellant storage pressure and higher propellant storage density, compared to the more common gas propellants such as krypton and xenon. Naphthalene also has excellent compatibility with the materials commonly used in the construction of satellites, eliminating the materials compatibility problems (corrosion), that increase the engineering challenge of other, more reactive solid propellants such as iodine. A functional proof of concept thruster is built and its performance is tested in the space simulation chamber, showing the reliable production of up to 0.6 mN of thrust.
... This is, for example, the case for some industrial implementations of zone refining processes for the growth and purification of crystals, where induc- tion heating is applied that may require frequencies of multiple MHz [9,10]. However, the efficiency of vacuum tube oscillators is low, leading to considerable energy loss in these processes [11,12]. Solid state technology promises improved efficiency in these applications, but as single turn coils are commonly used, the equivalent resistance of the load may be very low, demanding very high coil current to reach the required power deposition in the load [1]. ...
Abstract High frequency industrial induction heating processes typically employ resonant inverters to reach high efficiency at high power levels. Advancements in wide band gap (WBG) device technology has made it feasible to push the possible frequency of these processes into the MHz regime using solid state technology. Several topologies can be applied, each with advantages and drawbacks. This paper presents a current source resonant inverter (CSRI) employing a custom designed power module utilizing 1700V SiC MOSFETs for MHz operation of a high‐Q resonant tank for induction heating, which presents new challenges in the inverter module design. An integrated gate driver structure is demonstrated driving four MOSFETs in parallel in MHz operation. Theoretical analysis predicts substantial parasitic influence on inverter operation, and thus an inverter is constructed to provide experimental verification of MHz operation, while the challenges associated with high frequency CSRI operation are discussed. In the experimental inverter setup, the fabricated power module achieves >90% efficiency for a calculated reactive power of 170 kVA and 2.3 kW output power during unloaded operation, validating the inverter design for extension to higher power loaded operation.
... However, typical transistor structure, in comparison to vacuum tubes, has inherently more pronounced parasitic parameters, mainly parasitic capacitances, which complicates the usage of transistors in RF generation. A traditional solution to this problem is to utilize specialized RF transistor assemblies [2], which are optimized to reduce the parasitic capacitances and inductances, and hence allow such an assembly to operate efficiently on RF frequencies. Of course, the employment of such assemblies significantly increases the cost of an RF generator. ...
... The supply voltage VS for the generator was chosen to be 48 V. Considering that IRFB4020 device can handle 200 V of drain source voltage, and that the LC Tank of CMCD circuit provides a voltage rise of π units [2], the supply voltage must be about 4 times lower than 200 V, leaving a safety margin. A standard value of 48 V was chosen. ...
Radio frequency (RF) energy is widely used in many technological processes. One of the main components of a typical RF system is RF generator, which supplies powerful RF oscillations to the load. Transistor-based generators have many advantages, but usually utilize specialized RF transistor assemblies, which significantly increases the cost of the RF generator. In this study it was shown that a powerful high efficiency RF generator can be built using cheap non-specialized MOSFETs. The test generator utilizing IRFB4020 MOSFETs was built using Current Mode Class D circuit, which allowed the generator to achieve an efficiency of 89% at an output power of 200 W supplied to a 50-ohm load.
... Solid-state amplifiers are attractive due to their small size, high stability, and careful power control. [21] In radiofrequency systems, it is crucial to use a suitable impedance matching network to control the power and transfer most of the energy from the source to the load. [22] The impedance can be matched to 50 ohms between the output of the source and the load (coil) using passive components, inductors, and capacitors. ...
... Unless this heat is dissipated, it is a significant problem in radiofrequency systems. [21] MOSFETs are specially designed components for radiofrequency circuits. However, the assembly of MOSFETs on printed circuit boards is difficult due to their physical structure and overheating. ...
In recent years, interactions of radiofrequency (RF) electromagnetic fields with biological tissue have become one of the most promising strategies for noninvasive cancer hyperthermia treatment. Despite the growing interest, there has been a scarcity of studies involving the detailed construction of a complete RF-hyperthermia (RF-HT) system. Here a low-cost and high-power RF-HT system is reported with a specific frequency which can be used in biological samples. A laboratory-constructed RF-HT system composed of a radiofrequency oscillator, radiofrequency driver, radiofrequency amplifier, radiofrequency matching network, and an induction coil applicator were constructed and characterized by a stepwise approach. Although the RF driver and amplifier were purchased as professionally designed kits, significant modifications were required for these components. The results showed that the RF-HT system was successfully constructed and tested at 13.56 MHz with a power as high as 400 W. As a preliminary biological experiment, cell culture medium exhibited an approximate 3 °C increase in temperature induced by the RF-HT device at 250 W for 10 min. Moreover, the developed system is suitable drug targeting, drug release, and cellular uptake and designed to be cost-effective for in vitro/in vivo studies involving cancer therapy.
... This is very simple type of ignition system, but it suffers from continuous erosion and sputtering of electrodes and need frequent cleaning or may need replacement after few days of operation. An electrode less, external RF antenna based ignition system was developed; here RF antenna needs to couple the RF power to the hydrogen plasma chamber through inductive coupling [9][10][11][12][13][14][15][18][19][20][21][22][23][24][25]. ...
... The article [9] describes the various types of principle of RF coupling, power absorption, skin effect, discharge, electron temperature, energy loss. The paper [10] describes design and implementation of highly efficient, low cost 13.56 MHz, 1.5 kW RF source for inductively coupled plasma, for atomic emission spectroscopy. ...
This paper presents study of a 6.78 MHz RF source with impedance matching network based inductively coupled plasma generator ignition system for an H-ion source. Two types of 10 turn RF antenna (solenoid coil) were developed, to couple the RF power to the ignition plasma chamber. The antenna's electric parameters were measured using Vector Network Analyzer (VNA). A copper conductor of 3 x 4 mm size with 10 turn solenoid coil was selected for simulation and experimental prototype antenna. Two L-types of (CCL and LCL C-capacitor and L-inductor) matching network were selected for impedance matching network for RF antenna. Initial simulations are carried out using ELSIE and LT-spice for frequency range from 5 to 8MHz. The matching network along with RF antenna was matched to ~ 50 Ωimpedance at 6.78 MHz with capacitive nature. An experimental prototype RF power source, 10 turn antenna (coil) and a matching network was developed to validate the simulation results. The prototype ignition system along with impedance matching network L-type with CCL was tested for inductively coupled hydrogen plasma generation and experimental results presented. Hydrogen plasma generation starts at minimum antenna coupled RF power of 150 watts, once initiated hydrogen plasma maintains to a minimum RF power of 10 watts.
