Proof mass electrical charge management is an important functionality for the ST-7-LTP technology demonstration flight and for LISA. Photoemission for charge control is accomplished by using deep ultraviolet (UV) light to excite photoelectron emission from an Au alloy. The conventional UV source is a mercury vapour lamp. We propose and demonstrate charge management using a deep UV light emitting diode (LED) source. We have acquired selected AlGaN UV LEDs, characterized their performance and successfully used them to realize charge management. The UV LEDs emit at a 257 nm central wavelength with a bandwidth of ∼12 nm. The UV power for a free-space LED is ∼120 µW, and after fibre coupling is ∼16 µW, more than sufficient for LISA applications. We have directly observed the LED UV light-induced photocurrent response from an Au photocathode and an Au-coated GRS/ST-7 proof mass. We demonstrated fast switching of UV LEDs and associated fast changes in photocurrent. This allows modulation and continuous discharge to meet stringent LISA disturbance reduction requirements. We propose and demonstrate AC charge management outside the gravitational wave signal band. Further, the megahertz bandwidth for UV LED switching allows for up to six orders of magnitude dynamic power range and a number of novel modes of operations. The UV LED based charge management system offers the advantages of small-size, lightweight, fibre-coupled operation with very low power consumption.

A solid silver-ligand complex, μ-oxolato-bis(ethylenediaminesilver(I)), was developed for formulating particle-free conductive metal-organic decomposition (MOD) inkjet inks. The complex comprises both a high molar silver content and solubility in inkjet compatible polar solvents. An aqueous ink formulation with 29.5 wt % silver content was developed and inkjet printed onto glass, polyethylene terephthalate, and polyimide substrates. A new hybrid thermal-photonic curing approach resulting in substantially improved electrical properties and substrate adhesion is presented. Silver conductive traces were measured to have bulk resistivity of 4.26 × 10 Ω m, which is 2.7 times that of bulk silver. One-pot complex synthesis yielded an easily isolated, and stable, solid product that can be formulated when needed thereby improving shelf life.

Lead Zirconate Titanate (PZT) is a commonly used piezoelectric material due to its high piezoelectric response. We demonstrate a new method of printing and sintering micro-scale PZT films with low substrate temperature increase. Self-prepared PZT ink was Aerosol-Jet printed on stainless steel substrates. After drying for 2 h in vacuum at 200°C, the printed PZT films were divided into two groups. The first group was traditionally sintered, using a thermal process at 1000°C for 1 h in an Argon environment. The second group was photonically sintered using repetitive sub-msec pulses of high intensity broad spectrum light in an atmospheric environment. The highest measured substrate temperature during photonic sintering was 170.7°C, enabling processing on low melting point substrates. Ferroelectric measurements were performed with a low-frequency sinusoidal signal. The remanent polarization (P r ) and coercive field (E c ) for thermally sintered PZT film were 17.1 lC/cm 2 and 6.3 kV/cm, respectively. The photonically sintered film had 32.4 lC/cm 2 P r and 6.7 kV/cm E c . After poling the samples with 20 kV/cm electric field for 2 h at 150°C, the piezoelectric voltage constant (g 33 ) was measured for the two film groups yielding -16.9 3 10 -3 (VÁm)ÁN -1 (thermally sintered) and -17.9 3 10 -3 (VÁm)ÁN -1 (photonically sintered). Both factors indicate the PZT films were successfully sintered using both methods, with the photonically sintered material exhibiting superior electrical properties. To further validate photonic sintering of PZT on low melting point substrates, the process and measurements were repeated using a polyethylene terephthalate (PET) substrate. The measured P r and E c were 23.1 lC/cm 2 and 5.1 kV/cm, respectively. The g 33 was -17.3 3 10 -3 (VÁm)ÁN -1 . Photonic sintering of thick film PZT directly on low melting point substrates eliminates the need for complex layer transfer processes often associated with flexible PZT transducers.

Precursor (Metal-organic decomposition (MOD)) inks are used to fabricate 2D and 3D printed conductive structures directly onto a substrate. By formulating a nanoalloy structure containing multiple metals, the opportunity to modify chemical and physical properties exists. In this paper, a copper-nickel bimetallic nanoalloy film was fabricated by mixing copper and nickel precursor inks and sintering them in vacuum. The individual elemental inks were formulated and characterized using SEM, EDS, and XRD. During thermal processing, elemental copper forms first and is followed by the formation of bimetallic copper-nickel alloy. The encapsulation of the underlying copper by the nickel-rich alloy provides excellent oxidation resistance. No change in film resistance was observed after the film was exposed to an oxygen plasma. Nanoalloy films printed using reactive metallic inks have a variety of important applications involving local control of alloy composition. Examples include facile formation of layered nanostructures, and electrical conductivity with oxidative stability.

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