TPL (United States)

This paper reports novel material and process technologies for near-zero Temperature-Coefficient Resistors (TCR) and zero temperature coefficient of capacitance (TCC) capacitors and their integration into organic or silicon packages for precision RF components. A new concept of self-compensating resistors, leading to zero TCR was explored and demonstrated for the first time, using heterogeneous resistor stack structures consisting of metal layers with positive TCR and semiconducting oxide layers with negative TCR. Zero TCC capacitors were demonstrated with a film-stack consisting of ceramic nanocomposites of positive TCC and negative TCC. In both cases, the film thickness was designed such that there is internal compensation in temperature deviation, which results in zero temperature-coefficient. Material models were developed for the film-stack to design the films for zero temperature-coefficient.

Summary form only given. Nanoparticle composites offer promise for construction of high voltage pulse-forming systems since they allow the combination of tunable dielectric constant and high dielectric strength. To estimate the expected lifetime of insulation subjected to high electric fields in actual use conditions it was necessary to determine the probability of failure as a function of electric field. This Weibull probability function is presented for a nanoparticle composite with a dielectric constant of 10. The implication of this result for the use of this material in actual use conditions is discussed.

The stacked Blumlein line is a concept that has been touted as a highly compact pulsed power system because it combines the functions of energy storage, voltage scaling, and pulse shaping into a single sub-system. As a result, two single stage Blumlein lines have been fabricated and tested using a polymer-ceramic composite dielectric. Examination of the breakdown of the dielectric near the DC voltage specification led to the understanding of the degree of voltage reversal experienced by the lines. Voltage reversal is compounded in a stacked arrangement. The voltage reversal and transients induced by the switch jitter in a stacked configuration require significant derating of the dielectric strength. Consequently, the system must be operated much below the intrinsic dielectric energy density, compromising efforts to design a compact pulsed power system. This paper presents the conclusion that for derating below 0.72, as is likely necessary, a stacked Blumlein line will contain more dielectric than a comparable stacked transmission line.

The design of compact pulsed power systems involves the trade between size, pulse length and pulse shape. A stacked Blumlein line with high dielectric constant material can deliver a voltage flattop to a matched load with an energy density similar to capacitor banks. By imbedding nano-scale titanate particles in an epoxy matrix, a composite material with a relative permittivity in the range of 30 to 60 may be realized without the drastic loss in dielectric strength associated with large area ceramics. So called ceramic loaded polymer dielectric employed in a Blumlein line facilitates the fabrication of a compact pulse forming line potentially suitable for driving loads of several tens of Ohms in the GW power range for greater than 100 ns. This paper describes the initial efforts to fabricate and test a parallel plate Blumlein incorporating ceramic loaded polymer dielectric. Two single-stage parallel plate Blumlein lines were fabricated with different ceramic loading. The lines were designed to yield a 50 ns pulse into a 6.25 Omega load. The Blumlein lines were designed to be charged to 62.5 kV, and both fabricated units held the charge voltage in static tests. A small railgap switch was fabricated for use with the Blumlein lines. A mid-plane knife-edge electrode was used to trigger the switch. The results of the tests are presented along with projections for the future development of this technology.

ABSTRACTTraditional coil-based eddy-current sensors are severely limited in their ability to detect small buried defects, defects under fasteners and deeply buried cracks and corrosion. TPL has developed eddy-current sensors and arrays based on the use of Giant Magnetoresistance (GMR) sensor elements. GMR offers high sensitivity, very wide bandwidth and low noise from DC to over 1 GHz. Coupled with the ability to fabricate GMR sensors with micron-level dimensions, these new eddy-current sensors offer an ideal technology for inspections requiring high spatial resolution and low-frequency, deeply-penetrating fields.

A new capacitive array sensor has been developed for process verification and NDE of polymers and composites. Unlike existing dielectrometer technology, the new sensor incorporates several innovations to maximize sensitivity to material properties while minimizing the effects of temperature, humidity and electromagnetic interference. Conventional dielectric measurement systems require sensors to be embedded within a material and discarded after a single use. Furthermore, conventional sensors are so sensitive to environmental variables that cure monitoring is based solely on changes in the material ionic conductivity; no absolute measure of cure state is possible. The configuration of these new sensors greatly reduces sensitivity to environmental variables and permits external, rather than embedded, measurement making both post-process cure verification and NDE possible. Since the sensor is not discarded, the cost per measurement is greatly reduced.