Ultra High Frequency Power Research Articles

Low Frequency Oscillations of Plasma Injected into an Open Magnetic Trap from an Independent Ultrahigh Frequency Source

Methods of plasma heating by electromagnetic waves, interaction of electro-magnetic waves with magnetoactive plasma, plasma turbulence and transport processes are investigated in the trap of the linear plasma device OMT2. An ultrahigh frequency (UHF) contactless method is used to fill the open magnetic trap by plasma. We propose a new method of open magnetic trap filling with plasma whereby plasma is injected in the trap along the magnetic field from an independent stationary UHF source. The source is located outside the trap and plasma formation in it takes place in the strongly nonuniform magnetic field, in the electron cyclotron resonance (ECR) regime by means of the UHF power. In this paper we study the efficiency of open magnetic trap filling by plasma and plasma low frequency (LF) oscillations in the trap.

CALIBRATION OF HIGH AND ULTRA-HIGH FREQUENCY POWER METERS IN THE RANGE OF UP TO 30 MHZ

High-frequency (HF) and ultra-high-frequency (UHF) power measurements are applied in various industries both in the development and design of radio-electronic equipment and in testing, commissioning, or repair. Since such measurements are one of the basic types of measurement for metrological support in the field of radio engineering and communication, it is necessary to ensure metrological traceability of the calibration of working standards and measuring instruments to standards on fundamental constants in wide frequency and dynamic ranges. The National primary standard of Ukraine for units of power of electromagnetic oscillations in coaxial paths reproduces units of power in the frequency range 0.03 … 18 GHz, and the frequency range of the nomenclature of watt-meters and power converters are much wider – from 9 kHz, and for some types of converters even from direct current. The calibration and measurement capabilities of HF and UHF power measurement of national laboratories of different countries were studied for the possibility of solving the issue of expanding the frequency range of calibration of HF and UHF power meters. The analysis of data on the calibration factor and the efficiency factor in coaxial paths with a resistance of 50 Ohm in the Database of Key Comparisons of the International Bureau of Weights and Measures was carried out. A study of possible solutions was carried out and a scheme was developed to reproduce a unit of power by units of voltage and resistance using a precision voltmeter Boonton 9242 RF for the calibration of measuring transducers Rohde&Schwarz NRP-Z55 and NRP6A in the frequency range from 0.1 … 30 MHz. A reproduction model was created based on the developed scheme, and the contributions of the reproduction model components to the calibration result and the corresponding uncertainties of the model components were estimated. The measurement uncertainty budget was drawn up based on the proposed calibration model of radio signal power measuring transducers.

Measurements of spatial distributions of electron density and temperature of 450 MHz UHF plasma using laser Thomson scattering

A capacitively coupled Ar plasma was produced by the ultra-high frequency power source (450 MHz) and the plasma parameters were studied by laser Thomson scattering. It was found that a very high density plasma with a low electron temperature was realized; the electron density ne is around (1.1–1.5) × 1018 m−3 and the electron temperature Te is around (1.7–2.1) eV. Radial profiles of ne and Te were obtained for different pressures and powers. In all the conditions explored, ne had a single-center-peak profile, while Te profiles were relatively flat along the electrode.

A UHF/UWB Hybrid RFID Tag With a 51-m Energy-Harvesting Sensitivity for Remote Vital-Sign Monitoring.

A novel ultra-high frequency (UHF)/ultra-wideband (UWB) hybrid RFID tag is reported for object-specific remote vital-sign monitoring application. The tag achieves a record energy-harvesting sensitivity at UHF band by codesigning a meander dipole antenna and a passive rectifier. The especially high quality-factor makes the frontend sensitive to near-field motions such as heartbeats and respiration in a wearable setting. The custom CMOS IC of approximately 1-μW power consumption builds around a low-power UWB transmitter and converts variations of the supply voltage to the impulse repetition rate. The tag consisting of the IC and UHF/UWB antennas requires no other discrete components and features a size of 4.2 cm × 2.9 cm and a weight of 0.93 g. A long-distance experiment verifies that the tag can be wirelessly powered up at 51 meters from a 4-W equivalent-isotropic-radiation-power (EIRP) UHF transmitter. Remote vital-sign monitoring is validated on a human subject, in which the UHF power source is placed 2 meters away from the subject with a power emission of less than 20 dBm. This work proposes a first-of-its-kind remote vital-sign monitoring scheme based on a noncontact wearable tag. The design of the far-field energy-harvesting frontend with a record sensitivity serves as a reference for future works on battery-free remote sensors.

Development and plasma characterization of an 850 MHz surface-wave plasma source

This work presents a simple design of surface wave plasma (SWP) source based on cylindrical cavity excited by ∼ 850 MHz ultra high frequency (UHF) wave. The cavity equipped with four rectangular slots demonstrates the usefulness of a large aperture coupling for plasma generation using top-wall excitation. The UHF power is coupled to the plasma through an upper dielectric wall placed at the open end of a coaxial transmission line that is short-circuited at the other end to construct a coaxial transmission line resonator. Using high-frequency microwave simulation the structure of the cylindrical cavity and the slots are designed and fabricated. Numerous plasma diagnostic methods are used to study the plasma characteristics and the mechanism of surface wave (SW) plasma generation. The plasma generation capability of the source is investigated at various operating pressures and UHF powers. It is seen that reasonably radial uniform plasmas with a very high plasma density ∼ 1011 cm-3 can be produced by a wide variation of pressures from 10 mTorr to 180 mTorr. Further, the usefulness of this UHF plasma source for large area plasma application is realized.

Plasma diagnostic approach for high rate nanocrystalline Si synthesis in RF/UHF hybrid plasmas using a PECVD process

Hydrogenated nanocrystalline silicon (nc-Si : H) films intended for efficient nc-Si : H solar cells are usually made at the transition to the nanocrystalline regime using the plasma-enhanced chemical vapor deposition (PECVD) process. This change occurs within a sensitive process window and is affected by various deposition parameters. This paper reports a study of nc-Si : H films' fabrication by utilizing systematic plasma diagnostics. This work presents a novel approach for plasma processing using radio frequency (RF), ultra high frequency (UHF) and RF/UHF hybrid plasmas. Using careful analysis, efforts are made to investigate the radicals and plasma formation by changing the operating source power and silane (SiH4) concentration. The aim of this work is also to investigate the PECVD process and conditions favorable for the synthesis of nc-Si : H film. For the present study, we systematically use the optical emission spectroscopy (OES), normal, and RF-compensated Langmuir probe (LP) and vacuum ultraviolet absorption spectroscopy diagnostics. Measurements reveal that the OES diagnostic is consistent with the LP measurements. Investigation reveals that UHF power in addition to RF enables higher dissociation of H or SiH radicals and the production of higher plasma density. The combined effect of both RF and UHF sources is used as the hybrid plasma source. Measurements also reveal that inbetween SiH4 flow rates ∼20–30 sccm, there is significant change in the plasma characteristics that denotes the nc-Si : H−a-Si : H transition region. An atomic hydrogen density (nH) in the range ≈(8 − 10) × 1011 cm−3 and plasma density n0 ≈ (2 − 3) × 1011 cm−3 with a silane to hydrogen ratio of 1–2% with high crystallinity has been obtained. Along with the discussion on the effect of frequency on plasma chemistry, this explains the RF power coupling and the role of electrons and ions in plasmas with increasing frequency.

National primary standard for the unit of power of electromagnetic oscillations in waveguides and coaxial lines at frequencies of 0.03–37.5 GHz

The design of a modernized standard for reproduction and transfer of the unit of ultrahigh frequency power in waveguides and coaxial channels and some studies of this system are described.

Studies of emittance of multiply charged ions extracted from high temperature superconducting electron cyclotron resonance ion source, PKDELIS

For the high current injector project at Inter University Accelerator Centre, a high temperature superconducting electron cyclotron resonance (ECR) ion source, PKDELIS, would provide the high charge state ions. The emittance of the ECR ion source is an important parameter to design further beam transport system and to match the acceptances of the downstream radio frequency quadrupole and drift tube linac accelerators of the high current injector. The emittance of the analyzed beam of PKDELIS ECR source has been measured utilizing the three beam size technique. A slit and two beam profile monitors positioned at fixed distances from each other were used to measure the beam size. The digitized beam profiles have been analyzed to determine the emittance of various multiply charged ions. The variation of emittance with gas mixing, ultrahigh frequency power, and extraction energy are discussed in this presentation.

Synthesis and Characterization of Organic Thin Film Using Atmospheric-Pressure Plasma Polymerization

We developed a novel method of fabricating polymer film on a substrate at atmospheric pressure using atmospheric-pressure plasma polymerization (APPP) with a laboratory-made torch-type APPP apparatus. We used allylamine and acrylic acid as model monomers to optimize the polymerization conditions and evaluate the fabricated films. The APPP films were characterized by Fourier transform infrared (FT-IR) spectroscopy, contact angle measurement, atomic force microscopy (AFM), ellipsometry, X-ray photoelectron spectroscopy (XPS), deposition rate determination, and persistence measurement. Results showed that the properties of the APPP allylamine and acrylic acid films can be controlled by adjusting the polymerization parameter of ultrahighfrequency power.

The Development of Ultra-High Frequency Power 6H-SiC Vertical Static Induction Transistor with p-n Junction as a Gate

The Development of Ultra-High Frequency Power 6H-SiC Vertical Static Induction Transistor with p-n Junction as a Gate

Behavior of hydrogen atoms in ultrahigh-frequency silane plasma

We have investigated the behavior of the absolute density of hydrogen (H) atoms in ultrahigh-frequency (UHF), (500 MHz) silane (SiH4) plasma by using a vacuum ultraviolet absorption spectroscopy technique with a microdischarge hollow cathode lamp. In the UHF plasma using SiH4 highly diluted with hydrogen molecule (H2) at a pressure of 20 Pa, an UHF power of 1000 W, and a total flow rate of 200 sccm, the absolute density of H atoms slightly increased from 7.4×1011 to 7.9×1011 cm−3 with increasing the SiH4 flow rate ratios from 0% to 2.5% and then the H atom density decreased at the ratio of 5%. The decrease of the density is due to the increase of the reaction between the H atom and the SiH4 molecule. The behavior of the absolute density of H atoms was compared with that of the Balmer α(Hα) emission intensity. It was found that the behaviors of the absolute H atom density and the Hα emission intensity were quite different. Moreover, the kinetics of H atom density in SiH4 plasmas have been clarified on the basis of measured results.

The Correlation between an Electric Field and the Metastable Chlorine Ion Density Distributions in an Ultrahigh-Frequency Plasma

The electric field strength in an ultrahigh-frequency (UHF) plasma, as well as in an inductively coupled plasma (ICP), is measured with an electrostatic probe as a function of the radial and azimuthal positions of the plasma reactor. On comparing the electric field distribution with the radial density profile of metastable chlorine ions measured by Doppler-shifted laser-induced fluorescence, the electric field distribution is determined to be positively correlated to the ionization rate distribution in the UHF plasma, while that in the ICP seems to be less dependent on the electric field distribution. This phenomenon probably arises due to the large difference in the discharge frequency between the UHF plasma and the ICP. No remarkable azimuthal dependence of the radial average velocity and the temperature of the metastable Cl+ is observed, indicating that the two-dimensionally uniform plasma is produced by UHF power through a spokewise antenna.

マルチウィンドウ型アンテナを用いた極超短波プラズマ源

A new plasma source using a ultra high frequency (UHF) power radiated by a multi-window type antenna was developed. The UHF power was confined in a re-entrant type cavity resonator and radiated from 6 (six) quartz windows which were located on the bottom plate of the cavity. The production efficiency of UHF plasma was improved employing the new antenna structure. The radial non-uniformity of the ion current was less than ±5% at the plasma density of 1011 cm-3. The value is applicable for the φ300 mm wafer processing. Some preliminary results on SiO2 etch characteristics employing the perfluorocarbon gas chemistry shows that the plasma source will be suitable for the future fine etch processes.

New Ultra-High-Frequency Plasma Source for Large-Scale Etching Processes

A low temperature, uniform, high-density plasma is produced by an ultra-high-frequency (UHF) discharge using a new spokewise antenna. The plasma is uniform within ±5% over a diameter of 30 cm. The plasma density, 1×1011 cm-3, for low electron temperatures of 1.5-2.0 eV, is almost proportional to the UHF power even at a low UHF power. No magnetic field is needed to maintain a high-density plasma. Consequently, the plasma source is fairly simple and lightweight. The plasma source can accomplish a notch-free poly-Si etching profile with a high etching rate at a narrow space pattern of less than 0.3 µ m.

Low-temperature, uniform, and high-density plasma produced by a new ultra-high-frequency discharge with a spokewise antenna

A low-temperature, uniform, high-density plasma is produced by an ultra-high-frequency (UHF) discharge with a new spokewise antenna. The plasma is uniform within ±5% over a diameter of 20 cm. The plasma density, 5×1010 cm−3 for low-electron temperatures of 1.5–2.0 eV, is almost proportional to the UHF power even at a low-UHF power of 100 W. No magnetic field is needed to maintain a high-density plasma. Consequently, the plasma source is fairly simple and lightweight. The plasma source should ease serious problems in etching processes that use conventional high-density plasmas.

Application of the 30 MeV microtron for gamma and neutron activation analysis

Based on studies of variable multiplicity electron acceleration, the power-current microtron, a cyclic electron accelerator up to energies of 30–35 MeV has been developed at the Institute on Physical Problems of the Academy of Sciences of the USSR. The 1–1.5 kW electron beam of the microtron is comparable to the power output of modern linear accelerators operating at similar energies. At the same time, the microtron has a number of significant advantages, due to the simplicity of design of both accelerator and ultrahigh-frequency tract, the high efficiency of ultrahigh-frequency power utilization, good operating characteristics, strictly monochromatic electron beams (variations not exceeding ±50 keV at 30 MeV) and the possibility of continuously changing particle energy as required by the given experimental task.

Thermistor bridge with digital read-out for ultra-high frequency power measurements

Thermistor bridge with digital read-out for ultra-high frequency power measurements

Properties and Uses of Thermistors-Thermally Sensitive Resistors*

A new circuit element and control device, the thermistor or thermally sensitive resistor, is made of solid semiconducting materials whose resistance decreases about four per cent per centigrade degree. The thermistor presents interesting opportunities to the designer and engineer in many fields of technology for accomplishing tasks more simply, economically and better than with available devices. Part I discusses the conduction mechanism in semiconductors and the criteria for usefulness of circuit elements made from them. The fundamental physical properties of thermistors, their construction, their static and dynamic characteristics and general principles of operation are treated. Part II of this paper deals with the applications of thermistors. These include: sensitive thermometers and temperature control elements, simple temperature compensators, ultrahigh frequency power meters, automatic gain controls for transmission systems such as the Types K2 and L1 carrier telephone systems, voltage regulators, speech volume limiters, compressors and expandors, gas pressure gauges and flowmeters, meters for thermal conductivity determination of liquids, and contactless time delay devices. Thermistors with short time constants have been used as sensitive bolometers and show promise as simple compact audio-frequency oscillators, modulators and amplifiers.

Properties and Uses of Thermistors--- Thermally Sensitive Resistors

A new circuit element and control device, the thermistor, or thermally sensitive resistor, is made of solid semiconducting materials whose resistance decreases about four per cent per degree centigrade. The thermistor presents interesting opportunities to the designer and engineer in many fields of technology for accomplishing tasks more simply, economically, and better than with available devices. Part I discusses the conduction mechanism in semiconductors and the criteria for usefulness of circuit elements made from them. The fundamental physical properties of thermistors, their construction, their static and dynamic characteristics, and general principles of operation are treated. Part II of this paper deals with the applications of thermistors. These include: sensitive thermometers and temperature control elements, simple temperature compensators, ultrahigh frequency power meters, automatic gain controls for transmission systems, voltage regulators, speech volume limiters, compressors and expandors, gas pressure gauges and flowmeters, meters for thermal conductivity determination of liquids, and contactless time delay devices, Thermistors with short time constants have been used as sensitive bolometers, and show promise as simple, compact, audiofrequency oscillators, modulators, and amplifiers.

Properties and uses of thermistors — Thermally sensitive resistors

A new circuit element and control device, the thermistor, or thermally sensitive resistor, is made of solid semiconducting materials whose resistance decreases about four per cent per degree centigrade. The thermistor presents interesting opportunities to the designer and engineer in many fields of technology for accomplishing tasks more simply, economically, and better than with available devices. Part I discusses the conduction mechanism in semiconductors and the criteria for usefulness of circuit elements made from them. The fundamental physical properties of thermistors, their construction, their static and dynamic characteristics, and general principles of operation are treated. Part II of this paper deals with the applications of thermistors. These include: sensitive thermometers and temperature control elements, simple temperature compensators, ultrahigh frequency power meters, automatic gain controls for transmission systems, voltage regulators, speech volume limiters, compressors and expandors, gas pressure gauges and flow-meters, meters for thermal conductivity determination of liquids, and contactless time delay devices. Thermistors with short time constants have been used as sensitive bolometers, and show promise as simple, compact, audiofrequency oscillators, modulators, and amplifiers.