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Ben-Zvi, Ilan

Publications and source records attributed to Ben-Zvi, Ilan.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Lasing in 15 atm CO 2 cell optically pumped by a Fe:ZnSe laser

10 µm lasing is studied in a compact CO 2 -He cell pressurized up to 15 atm when optically pumped by a ∼50 mJ Fe:ZnSe laser tunable around 4.3 µm. The optimal pump wavelength and partial pressure of CO 2 for generating 10 µm pulses are found to be ∼4.4 µm and 0.75 atm, respectively. Without cavity optimization, the optical-to-optical conversion efficiency reached ∼10% at a total pressure of 7 atm. The gain lifetime is measured to be ∼1 µs at pressures above 10 atm, indicating the feasibility of using high-pressure optically pumped CO 2 for the efficient amplification of picosecond 10 µm pulses.

Tovey, Dana↗
DOE OSTI2021

Cryogenic operation of planar ultrananocrystalline diamond field emission source in SRF injector

Here, we report a demonstration of electron beam generation in a superconducting radio frequency (SRF) Teraelectronvolt Energy Superconducting Linear Accelerator 1.3 GHz gun equipped with a field emission cathode and operated at 2 K. The cathode is a submicrometer film of nitrogen-incorporated ultrananocrystalline diamond [(N)UNCD] deposited atop a Nb RRR300 cathode plug that is 4 mm in diameter. Measurements of the output current showed that it increased exponentially as a function of the gun gradient. Our results demonstrate a feasible path toward simplified fully cryogenic SRF injector technology. At a maximal gradient of 0.9 MV/m, a current density of 22 μA/cm2 was obtained [calculated as a 2.75 μA current over the total cathode surface area of π(2 mm)2]. One important finding is that the electron emitter made of (N)UNCD, a material long been known as a highly efficient field emission material, demonstrated a record low turn-on gradient of 0.6 MV/m. A hypothesis explaining this behavior is proposed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Cryogenic RF tests of US LARP DQW SPS-series cavities

Crab cavities are one of the several components included in the luminosity upgrade of the Large Hadron Collider (HL-LHC). For nominal operation, the cavities have to provide a nominal deflecting kick of 3.4 MV per cavity in Continuous Wave operation at 2 K. The requirement for an unjacketed cavity – bare cavity equipped with Higher-Order Mode (HOM) filters and field antenna – is to reach at least a deflecting voltage of 4.1 MV (20% margin) with the heat load to the 2 K bath below 10 W. Cryogenic RF tests confirmed the required performances in bare cavities, with several cavities exceeding the required voltage by more than 50%. However, the first tests of a Double-Quarter Wave (DQW) cavity with one out of three HOM filters did not reach the required voltage. The present paper describes the studies and tests conducted to understand the limiting factor in the operation of a DQW cavity with HOM filters in the most up-to-date prototypes produced in the US and based on the DQW SPS-series design. The recipe to meet the performance specification for a bare DQW cavity with HOM filters and exceed the voltage requirement by more than 35% is discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

A Ferroelectric Fast Reactive Tuner for Superconducting Cavities

A prototype FerroElectric Fast Reactive Tuner (FE-FRT) for superconducting cavities has been developed, which allows the frequency to be controlled by application of a potential difference across a ferroelectric residing within the tuner. This technique has now become practically feasible due to the recent development of a new extremely low loss ferroelectric material. In a world first, CERN has tested the prototype FE-FRT with a superconducting cavity, and frequency tuning has been successfully demonstrated. This is a significant first step in the development of an entirely new class of tuner. These will allow electronic control of cavity frequencies, by a device operating at room temperature, within timescales that will allow active compensation of microphonics. For many applications this could eliminate the need to use over-coupled fundamental power couplers, thus significantly reducing RF amplifier power.

43 PARTICLE ACCELERATORS↗