374 research outputs found
Thermal emittance measurements of a cesium potassium antimonide photocathode
Thermal emittance measurements of a CsK2Sb photocathode at several laser
wavelengths are presented. The emittance is obtained with a solenoid scan
technique using a high voltage dc photoemission gun. The thermal emittance is
0.56+/-0.03 mm-mrad/mm(rms) at 532 nm wavelength. The results are compared with
a simple photoemission model and found to be in a good agreement.Comment: APL 201
Cold electron beams from cryo-cooled, alkali antimonide photocathodes
In this letter we report on the generation of cold electron beams using a
Cs3Sb photocathode grown by co-deposition of Sb and Cs. By cooling the
photocathode to 90 K we demonstrate a significant reduction in the mean
transverse energy validating the long standing speculation that the lattice
temperature contribution limits the mean transverse energy or thermal emittance
near the photoemission threshold, opening new frontiers in generating
ultra-bright beams. At 90 K, we achieve a record low thermal emittance of 0.2
m (rms) per mm of laser spot diameter from an ultrafast (sub-picosecond)
photocathode with quantum efficiency greater than using a
visible laser wavelength of 690 nm
Role of plasma-induced defects in the generation of 1/f noise in graphene
It has already been reported that 1/f noise in graphene can be dominated by fluctuations of charge carrier mobility. We show here that the increasing damage induced by oxygen plasma on graphene samples result in two trends: at low doses, the magnitude of the 1/f noise increases with the dose; and at high doses, it decreases with the dose. This behaviour is interpreted in the framework of 1/f noise generated by carrier mobility fluctuations where the concentration of mobility fluctuation centers and the mean free path of the carriers are competing factors. Published by AIP Publishing
Development of a battery real-time state of health diagnosis based on fast impedance measurements
Recommended implementation of electrical resistance tomography for conductivity mapping of metallic nanowire networks using voltage excitation
The knowledge of the spatial distribution of the electrical conductivity of metallic nanowire networks (NWN) is important for tailoring the performance in applications. This work focuses on Electrical Resistance Tomography (ERT), a technique that maps the electrical conductivity of a sample from several resistance measurements performed on its border. We show that ERT can be successfully employed for NWN characterisation if a dedicated measurement protocol is employed. When applied to other materials, ERT measurements are typically performed with a constant current excitation; we show that, because of the peculiar microscopic structure and behaviour of metallic NWN, a constant voltage excitation protocols is preferable. This protocol maximises the signal to noise ratio in the resistance measurements—and thus the accuracy of ERT maps—while preventing the onset of sample alterations
Implementation of electrical resistance tomography for conductivity mapping of nanostructured transparent conductor materials
Molekularna karakterizacija starog stabla masline Olea europea na Brijunima analizom SSR markera
Investigations were carried out on molecular characterization of a 1600 years old olive tree located on the Brijuni islands (Croatia) by SSR markers analysis. Measurements of fruits and leaves features were carried out on the old tree Brijunka and on the standard Istrian cultivar Buga (Buža). Measurement data on fruits and leaves
were calculated statistically.Istraživanja obuhvaćaju molekularnu karakterizaciju 1600 godina starog stabla masline Olea europea na Brijunima analizom SSR markera. Provedene su izmjere svojstava ploda i lišća starog stabla masline Brijunke i standardne istarske sorte Buga (Buža). Rezultati istraživanja obrađeni su varijacijsko-statistički
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