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Experimental testing of electron beam formation, transport, and depressed collection is performed in a beamstick for a 670 GHz extended interaction klystron with a 25 kV, 100 mA nominal operating point. Beam transmissions of 77–86% are achieved through a 125 micron diameter by 1.7 cm long beam tunnel.
The development of new terahertz power amplifiers at 0.67, 0.85 and 1.03 THz presents significant challenges in both design and fabrication. This paper describes the fabrication challenges and test results of a Beamstick and EIK at 0.67 THz.
A W-band extended interaction klystron (EIK) driven by a 19.5-kV, 3.5-A sheet beam is being developed. Simulations using the 3-D particle-in-cell codes MAGIC1 and ICEPIC2 predict saturated output power levels of 8–10 kW with a saturated gain >30 dB and small signal gain >40 dB. A beamstick has been successfully fabricated and tested, transporting 98% of the emitted current through a 0.4-mm ×...
Extended interaction klystrons have been demonstrated at frequencies up to 218 GHz CW and 229 GHz pulsed. Modern design, fabrication, and measurement technologies show promise of extending their operation into the THz range of frequencies. Extensive use of 3D physics-based design tools, in particular, has enabled us to select promising design approaches and to understand phenomena that affect EIK...
The principal advantage of multiple-beam devices resides in the fact that beamlets propagate in their own individual beam tunnels [1], enabling non-intercepting beam transport at lower beam voltages and/or guiding magnetic fields, and simultaneously allowing for greater flexibility in tailoring the overall beam perveance to optimize beam-wave interaction. This flexibility is exemplified by several...
The North American Monsoon (NAM) contributes critical summer moisture to the U.S. Southwest from July through September, but instrumental records of monsoon precipitation are limited to 100 years or less. Tree-ring investigation offers a means of improving our understanding of its long-term spatial and temporal variability. Available evidence indicates the stable-carbon isotopic composition (δ ...
Key performance characteristics that guide the selection of an amplifier for various applications are gain, power, linearity, and efficiency. In this paper, these parameters are contrasted for two amplifier configurations: a single-beam amplifier with stages placed in series vs. a multi-beam amplifier with cascading stages. Based on MAGIC-3D simulations, while gain and efficiency are comparable, the...
A sheet-beam Extended Interaction Klystron (EIK) is being developed at W-band to demonstrate the enhanced power capability, compactness, and relatively high gain per unit length that have been predicted for the device. The EIK is powered by a 19.5-kV, 3.3-A sheet beam having dimensions of 0.32 mm × 4 mm. A beamstick for the device has achieved 98% current transport efficiency over a distance of 2...
The constitutive androstane receptor (CAR) transactivation can occur in the absence of exogenous ligand and this activity is enhanced by agonists TCPOBOP and meclizine. We use biophysical and cell-based assays to show that increased activity of CAR(TCPOBOP) relative to CAR(meclizine) corresponds to a higher affinity of CAR(TCPOBOP) for the steroid receptor coactivator-1. Additionally, steady-state...
It is likely that phylogroup 2 lyssaviruses circulate within bat reservoirs. We adapted a pseudotype (pt) neutralisation assay (PNA) to a multiplex format enabling serosurveillance for Lagos bat virus (LBV), Mokola virus (MOKV) and West Caucasian bat virus (WCBV) in a potential reservoir, the African straw-coloured fruit bat, Eidolon helvum. Highly correlated titres were observed between single and...
Summary form only given.The development of terahertz power amplifiers presents significant new challenges as it brings into focus design, fabrication, and measurement issues that are not important factors at lower frequencies. We will describe our design approach to meet these challenges with particular emphasis on a 0.67 THz Extended-Interaction Klystron (EIK).One of the key design challenges is...
Both the generation and the stable transport of high-perveance, relatively low-voltage sheet beams suitable for millimeter wave and submillimeter wave amplifiers are quite challenging. We have designed and fabricated a beam stick to validate our design1 of a 19.5 kV, 3.5 A sheet beam having a cross section of 0.3 × 4 mm, whose parameters were selected to drive a W-band extended interaction klystron...
Serpentine traveling-wave tubes (TWTs) are a class of vacuum electronic devices capable of wideband (25%), high power performance. However, their bandwidth depends critically on the path length along a half-period of the serpentine waveguide (from gap to gap). At THz frequencies (200 to 1000 GHz), beam tunnel diameters well below 200 μm are required to achieve bandwidth ~20%. On this scale, fabrication...
The development of terahertz power amplifiers presents significant new challenges as it brings into focus design, fabrication, and measurement issues that are not important factors at lower frequencies. In this paper, we describe our design approach to meet these challenges with particular emphasis on a 0.67 THz Extended-Interaction Klystron (EIK). This device is being designed to generate a peak...
A sheet-beam Extended Interaction Klystron (EIK) is an attractive MMW amplifier because of its enhanced power capability, compactness, and relatively high gain per unit length. However, an intrinsic problem with a sheet beam amplifier is its susceptibility to multimoding, which results because the width of the device is typically larger than a wavelength. Even in its ideal configuration, a sheet beam...
The stable transport of high-perveance, low-voltage sheet electron beams is a key requirement for the successful development of compact, high-power sheet beam amplifiers. We describe a beam stick to demonstrate the transport of such a beam (19.5 kV, 3.5 A) in a solenoidal magnetic field of about 8.5 kG. The beam stick consists of a novel sheet beam gun having single-plane convergence of a factor of...
Extended Interaction Klystrons have been demonstrated at frequencies up to 218 GHz CW and 229 GHz pulsed. Modern design, fabrication, and measurement technologies show promise of extending their operation into the THz regime. This paper describes the challenges and some novel approaches to the development of EIKs operating at 670, 850 and 1030 GHz, while simultaneously meeting demanding requirements...
To produce an EIK working at THz frequencies, departure from traditional fabrication techniques is required. This paper describes the investigation and results of various fabrication techniques and their suitability for application in a VED.
A new concept for a compact high-gain multiple-beam TWT amplifier is introduced. To illustrate the concept, we present the design of a three-beam 220-GHz serpentine TWT amplifier. MAGIC-3D particle-in-cell code simulation results predict that the device should be capable of a peak power of 73 W and saturated gain of 42 dB over an instantaneous bandwidth of 50 GHz (23%), when powered by three 100 mA,...
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