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Section 6: Electromagnetic Field Modeling of Diamond CVD Reactors
Published in Mark A. Prelas, Galina Popovici, Louis K. Bigelow, Handbook of Industrial Diamonds and Diamond Films, 2018
In order to verify the cavity resonant mode, the radial component of electric field strength at the cavity outer wall was measured by calibrated micro-coax electrical probes inserted through the cavity wall versus z and ϕ [Zhang et al. 1990]. The center conductor of the probe is inserted 2 mm beyond the inside surface of the cavity side walls, and the other end is connected to a microwave power meter. Since the probe power reading is proportional to the square of the rms electric field strength normal to the inside cavity, the cavity resonant mode and the cavity stored energy can be determined using this technique [Zhang et al. 1990]. Probe experiments were done by measuring the electric field strength at various z positions along the cylindrical cavity wall of the microwave plasma reactor during diamond thin film deposition. The microwave excitation frequency was 2.45 GHz, and the cavity height was adjusted to a position near 20.4 cm for a minimum reflected power condition. The result is shown in Fig. 6 where the resonant condition for the microwave cavity during a deposition process matches closely to the ideal TM013 mode. Additionally, the electric field was probed circumferential around the cavity. The field strength showed no significant variation along the ϕ direction as expected for the TM013 mode.
Photodetectors
Published in Robert G. Hunsperger, Photonic Devices and Systems, 2017
The light out of the coupler is split—one path is used to monitor laser power and the other goes to the photodetector under test. The resulting photocurrent passes through an attenuator and is measured with a microwave power meter. The photodetector responds to the envelope of the optical power. The difference frequency is swept and the measured change in output of the photodiode at the microwave power meter determines the frequency response.
Mathematical Modeling of Dielectrically-Enhanced Drying
Published in Ian Turner, Arun S. Mujumdar, Mathematical Modeling and Numerical Techniques in Drying Technology, 1996
Peishi Chen, Philip S. Schmidt
The integral method was used successfully in the simulation of MWenhanced drying of wood veneers, gypsum wallboard, glass beads, polymer pellets, and alumina beads [19,25]. The experiments on beds of glass beads, polymer pellets, and activated alumina beads were conducted in a microwave drying oven with controlled temperature and air flow rates [19]. Samples of wet materials were placed in an insulated tray 38×27cm in length and width, respectively, and 5 cm deep, with the air in crossflow over the surface. The tray sits on an electric balance that continuously measures mass to a resolution of 1 gram. Sample temperatures were measured at different locations using fluoro-optic temperature probes with a resolution of 0.1∘C. Forward and reflected power were measured with a directional coupler feeding a Hewlett Packard 438A microwave power meter. Calorimetric tests on the power meter/directional coupler in the power range of interest indicated an accuracy of 10% for the incident power onn these samples. Physical properties of the polymer pellet sand activated alumina and the drying conditions for the experiments are listed in Table 1. The polymer, a styrene compound, is essentially nonhygroscopic. The adsorption characteristics for activated alumina, which is highly hygroscopic, were taken from the study of Toei et al. [27]. The liquid-phase and bound moisture transfer coefficients were estimated by trial-and error to give the best fit to the measured drying data at two air temperatures.
Plasma cleaning under low pressures based on the domestic microwave oven
Published in Journal of Microwave Power and Electromagnetic Energy, 2021
Li Wu, Zhuang Liu, Wencong Zhang, Xi Feng
The schematic of low-pressure plasma ignition system with a microwave oven is shown in Figure 3. The experimental system consisted of a glass conical bottle, a microwave oven (P70D20TL-D4, Galanz, China), a vacuum gauge (552, Testo, Germany) and a vacuum pump (FUJ-PCV, Fujiwara, Japan), a microwave power meter (AV2433, the 41st Institute of China Electronic Technology Group Corporation, China) and a directional coupler (L00PE22DC40A10N, Euler Microwave Element Ltd., China). To investigate the effects of microwave power on the plasma property, the directional coupler was added between the microwave oven cavity and the magnetron. A high voltage power supply was employed to control and adjust the output power of magnetron. Two tubes as the gas inlet and outlet were inserted into the bottle through a stopper at the bottle mouth. The conical bottleneck was placed in a cylindrical cut-off waveguide on the top surface of the microwave oven. The gas inlet tube was connected to the gas tank while the outlet was in series with the vacuum pump. The vacuum gauge was employed in this system to supervise the pressure in the bottle in real time. The input and reflect power of the system were measured by the microwave power meter.
Effect of the rotating metal patch on microwave heating uniformity
Published in Journal of Microwave Power and Electromagnetic Energy, 2018
Qian Meng, Junqing Lan, Tao Hong, Huacheng Zhu
Based on a BJ-22 rectangular waveguide and a microwave oven, an experimental system is set up to validate the proposed model, which is shown in Figure 3. A circulator is used to protect the microwave generator and a directional coupler is employed to detect the microwave power. An AV2433 microwave power meter connected to the coupler is used to measure the output power of the microwave generator at real time. The microwave is transmitted along the circulator, the directional coupler and then fed into the microwave oven. Two optical fibres connected to a FISO UMI-8 optical fibre thermometer are used to measure the temperature of two points of the potato, which will be described in the next section. The potato is fixed by a fine line and hanging in the microwave oven. During the whole heating process, the potato will stay static while the turntable will be rotating.
Microwave power absorption profile of detergent surfactant agglomerates during microwave heating
Published in Drying Technology, 2018
Muhammad Y. Sandhu, Sharjeel Afridi, Qari Khalid, Ian C. Hunter, Nigel S. Roberts
A bi-directional digital microwave power meter from GAE is connected to the output port of the isolator. This device measures the electromagnetic signals traveling in both forward and reverse direction. The bi-directional power meter consists of a bi-directional waveguide coupler, diode detector, and a digital voltage meter.