DAVIS SITE FACILITIES

The Microwave/Millimeter Wave Instrumentation and Quasi-optics Facility

The microwave/millimeter wave instrumentation and quasi-optics facility is housed in ECE space in E-II (Room 3182) and is shared with Professor G. R. Branner. The facility possesses a number of state-of-the-art systems: HP8510B automated vector network analyzers, HP 8757 scalar network analyzers, HP sweepers, HP 8910B noise figure test set with 86671B synthesizer, HP spectrum analyzers, an HP 3048A phase noise system with 8662A synthesizer together with millimeter wave source and measurement capability up to 170 GHz. The primary DAS research in this facility has been directed toward monolithic, quasi-optical grid arrays for high power millimeter wave power generation and beam control and the use of novel nonlinear transmission lines for ultrashort pulse generation. Major advances have resulted in new concepts for automotive collision avoidance radar and phased array antennas for satellite communications.

The High-Power Microwave Source and Plasma Interaction Laboratory

The high power microwave source and plasma interaction laboratory (160 Walker Hall) comprises 1800 square feet and possesses 0.5 MW ac service and features a chilled water recirculation system, thereby permitting high average power experiments. Several large (~1-2m) plasma chambers permit the careful investigation of the physics associated with laser fusion by scaling the laser wavelength to the microwave region and consequently the micron-millimeter sized targets to meter scale lengths. Microwave-plasma interactions are used to model laser-plasma interactions with applications to the inertial confinement fusion research program. Basic laboratory studies are also conducted on the use of reflectometry as a diagnostic for the determination of density profiles and fluctuations in magnetic fusion plasmas. Significant activity is being devoted to the development of high current density oxide cathodes. A new superconducting magnet solenoid is utilized for the development of high power 94 GHz harmonic gyrotron's and gyro-TWTs. A computer controlled TWT test station provides drive power from 40-100 GHz for the gyro-TWT developments as well as solid state quasi-optical frequency multiplier array studies. In addition to the above, the building also contains a well-equipped machine shop where experimental devices are fabricated in support of both Davis and Livermore based DAS programs.

The Far-Infrared and Millimeter Wave Magnetic Fusion Plasma Diagnostics Laboratory

The far-infrared and millimeter wave magnetic fusion plasma diagnostics laboratory (Room 1209, EII) was established to provide novel diagnostics instrumentation for next generation tokamak magnetic fusion plasma devices. Recent developments have ranged from a monolithic imaging millimeter wave receiver array for the determination of temperature fluctuations to an ultrashort pulse reflectometer system for the measurement of density profiles and density fluctuations. Unique instrumentation includes tunable carcinotron sources operating at frequencies as high as 420 GHz as well as novel optically pumped molecular lasers operating up to 3 THz.

This laboratory is also home to both manual and automated probe stations for characterizing millimeter-wave circuits and grid arrays. Below is a photograph of two probe stations. The unit on the right is an automated system which is utilized to characterize thousands of devices contained on monolithic diode arrays and which has proved invaluable in the characterization of high speed switch arrays for moderate pulse reflectometry. On the left is a probe system outfitted with millimeter wave Cascade probes which permit measurements from a dedicated HP8510 B millimeter wave network analyzer and Tektronix 11802 50 GHz digital sampling oscilloscope.

Microfabrication Facilities

The Ultrafast Optics and Optoelectronics Facility

The ultrafast optics and optoelectronics research facility consists of five substantial laboratory spaces shared by A. Dienes, J.P. Heritage, O. Solgaard, and A. Knoesen and their students. Major facilities include a new large frame Ar-ion laser, a 50 femtosecond Kerr-Lens modelocked Ti:Sapphire laser, a Modelocked CW YAG laser and a 150 femtosecond tunable NaCl color center laser. A new high energy Q-switched and doubled YLF is used to pump a home-built Ti:Sapphire amplifier. Significant effort is also directed toward the development of microphotonics technology using Micro Electro Mechanical Systems (MEMS). These facilities span two large research grade optical tables in two separate laboratory spaces. Four additional medium sized research grade optical tables support a Q-switched YAG and a multi-wavelength test bed for characterization of electro-optic Fabry-Perot modulators. Diagnostic equipment include high speed digital sampling oscilloscopes and laboratory data acquisition computers. Two laboratory workstations are networked to a number of departmental workstations for numerical simulation and graphical analysis with the solid state

50 femtosecond Kerr-Lens modelocked Ti:Sapphire laser

Advanced Light Source Laboratory

The Advanced Light Source Laboratory (161 Walker Hall), developed by Professor Stephen Cramer, has extensive facilities and equipment which supports work on various kinds of spectroscopy aimed at the characterization of the structure and function of metals in biological systems. Many of the critical reactions in biology, such as nitrogen fixation and photosynthesis, rely on metal centers to bind substrates and accelerate their conversion to products. A better understanding of these events is important both scientifically and for new catalyst technology.

The primary emphasis of this laboratory is in the development of new x-ray spectroscopy tools for characterizing the above stated metal centers. As general users and members of Participating Research Teams, beamlines at synchrotron radiation sources such as the Advanced Light Source in Berkeley, the National Synchrotron Light at Brookhaven, and the Stanford Synchrotron Radiation Lab are also available to our faculty and students.

The techniques include (1) soft x-ray spectroscopy of biological metals, (2) site-selective x-ray absorption using high resolution x-ray fluorescence, and (3) x-ray magnetic circular dichroism.

Computer Facilities

The group possesses considerable microwave circuit and structure design and simulation capability which will play a major role in the proposed plasma diagnostic developments. Three dedicated workstations are outfitted with commercial software including 3-D, finite element EM codes (HP's HFSS and Ansoft's SI Eminence), 2-D method of moments codes (HP's Momentum) and linear and nonlinear microwave circuit analysis modeling codes (HP's MDS). For example, the figure below shows a dedicated SPARC workstation running the Ansoft 3-D E-M simulator SI Eminence to optimize the coupling probe in subharmonic mixer development. The simulator's capabilities are further displayed in the following figure which shows the calculated E-field progression in the slow bow-tie antennas developed by the group. In addition, noncommercial 3-D codes such as EIGER (EM), DSI3D (EM, unstructured 3-D mesh), NEC-4 (method of moments EM code), TSAR (EM, FDTD), TOPAZ3D (thermal), and NIKE3D (structural/mechanical) are available for detailed electro-mechanical modeling of array cooling structures. The figure above shows the dedicated Power Macintosh employed for FIR interferometry/polarimetry reconstructions. A variety of plasma simulation codes are available which range from 1-D electrostatic codes to a 2-D electromagnetic, particle code (ZOHAR) through 2-D hybrid codes, where the ions are represented as particles and the electrons as a fluid. In addition, the group possesses access to a variety of supercomputers.