The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Summary form only given. A method has been developed to launch macroscopic flyer plates using the intense magnetic pressure produced by the Sandia Z accelerator. The accelerator is capable of producing >20 MA current pulses with ~200 ns rise-time into a short circuit load, generating intense magnetic fields within the anode cathode (AK) gap. The resulting Lorentz force enables the Z accelerator...
Summary form only given. A capability to produce quasi-isentropic compression of solids using pulsed magnetic loading on the Sandia Z accelerator has recently been developed and demonstrated. The accelerator is capable of producing >20 MA current pulses with ~300 ns rise-time into a short circuit load, generating intense magnetic fields within the anode cathode (AK) gap. With proper design of the...
Summary form only given. Laboratory experiments that employ petawatt lasers are rapidly approaching parameter regimes once thought to be the exclusive domain of compact astrophysical objects. In fact, experiments and simulations of petawatt lasers impinging on solid density targets have always shown that some fraction (usually ~10-50%) of laser energy couples to hot electrons in the target, which...
Summary form only given. A new approach to materials science at extreme pressures has been developed on the OMEGA laser, using a ramped plasma piston drive. The laser drives a shock through a solid plastic reservoir that unloads at the rear free surface, expands across a vacuum gap, and stagnates on the metal sample under study. This produces a gently increasing ram pressure, compressing the sample...
Summary form only given. The equation of state and opacity of warm dense helium (1<p<10 g/cm3, 0.5<T<5 eV) is essential for addressing a variety of astrophysical problems, such as the cooling rate of white dwarfs or the miscibility of H/He in the interior of giant planets. High-pressure experimental data on dense helium are sparse, and in particular none exist in the region of direct astrophysical...
Summary form only given. Ultra-shallow junctions (USJ) are required for fabrication of sub-0.1 mum transistors in semiconductor integrated circuits. The most straightforward fabrication method is to extend the beam-line ion implantation technology to ultra-low energies (100s eV to a few kV). Due to space charge induced divergence, low energy beams are restricted to low currents resulting in lower...
Summary form only given. We have investigated the characteristics of VHF capacitively coupled plasmas produced in a modified applied materials chamber. The chamber had a 14-inch diameter upper electrode (source) that was driven at 10 to 160 MHz and a 300 mm diameter electrostatic chuck with a ceramic process kit that was driven at 13.56 MHz (bias). Diagnostics employed include RF diagnostics to measure...
Summary form only given. Energetic ion bombardment of substrates in capacitively coupled plasma (CCP) sources and the resulting ionization from secondary electrons are critical to sustaining the plasma. During operation of CCPs for plasma materials processing, the surface condition of substrates often changes due to etching and deposition phenomena. As a result, the secondary electron emission coefficient...
Summary form only given. A very effective inductively coupled plasma (ICP) source free of capacitive coupling and transmission line effect is developed according to Godyak's concept. The discharge is driven via six toroidal ferromagnetic cores whose primary windings are connected to an RF power source operated at 400 kHz. The source operates in a wide range of the input RF power, thus, it is able...
Summary form only given. Multi-frequency RF capacitive discharges are the current state-of-the-art technology in dielectric etch. Very high frequency (VHF) sources are used for controlling plasma density. Low frequency sources are used to control ion dynamics in the sheath in front of the processing wafer. These two frequency selections allow for nearly independent control of ion flux and ion energy...
Summary form only given. Doped nanotube is a possible candidate of a nano diode for the nanoelectronic device. In order to dope the N or P type elements into a carbon nanotube (CNT), it is necessary to carry on the deformation of the tube such as opening the end of the tube or cutting the side of the tube. After filling the elements, those opening areas of the tube should be closed through the reconstruction...
Summary form only given. Plasma assisted molecular beam epitaxy (PAMBE) of III/V-group nitrides is a potential alternative to metal-organic chemical vapor deposition (MOCVD) for fabrication of high quality wide band gap semiconductor devices. The main advantage of PAMBE over MOCVD is the use of solid gallium evaporated in a Knudsen cell in conjunction with a pure nitrogen plasma source to generate...
Summary form only given. The development of conventional cavity gyrotrons at 140 GHz with 1-MW, CW output power at Forschungszentrum (FZK) Karlsruhe is mainly linked with the construction of the new superconducting stellarator W7-X at IPP Greifswald, Germany. For W7-X, 10 MW of electron cyclotron heating (ECRH) is planned and will be produced by ten gyrotrons each with a power of 1-MW. The gyrotrons...
Summary form only given. High-power, long-pulse or CW millimeter-wave sources are required for electron cyclotron heating (ECH) and current drive in magnetic fusion experiments. To further reduce system cost and improve reliability we have developed and built a prototype 110 GHz, with output power greater than 1 MW and a single-stage, depressed collector. In this paper, we report on the long-pulse...
Summary form only given. To realize continuous-wave (CW) operation of millimeter-wave gyrotrons at megawatt (MW)-power levels, these devices must operate at very high-order modes. To excite such an operating mode and to drive it into the regime of MW-level operation with high efficiency requires careful consideration of the startup scenario through which the operating parameters of the device are...
Summary form only given. The stability issue in the gyrotron backward wave-oscillator (gyro-BWO) is the major limitation of demonstrating its capability of broadband and continuous tunability. A time-dependent code is employed to examine the stability of gyro-BWO for either magnetic-field or beam-voltage tuning. Numerical results indicate that shortening the interaction length stabilizes the operation...
Summary form only given. A broadband, W-band gyro-traveling-wave-tube (gyro-TWT) amplifier is currently under development at CPI. The gyro-TWT will be used as a driver for other previously developed and planned high-power W-band gyro-amplifiers. The device was designed to achieve 500 W peak output power and 200 W average output power at 96 GHz center frequency with a fall-width-half-maximum bandwidth...
Summary form only given. In the paper the results of the theoretical and experimental studies of the non-stationary dynamics of the sub-relativistic K-band gyro-BWO with external reflections are presented. The gyro-BWO is an attractive source of powerful microwave signals due to frequency tunability, which can be realized by varying the magnetic field or the beam voltage. From the other hand, in comparison...
Summary form only given. The dynamics of axial mode competition in the gyrotron backward-wave oscillator (gyro-BWO) has been investigated in theory and experiment. Because of the difference in field-shaping processes, the axial modes of the gyro-BWO each exhibit a distinctive asymmetry in field distribution along the axis. Multi-mode particle simulations reveal a consistent pattern of axial mode competition...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.