Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “cavity”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Vertical-cavity surface-emitting phase shifter

This study proposes a novel technique for a 2D beam steering system using hybrid plasmonic phase shifters with a cylindrical configuration in a 2D periodic array suitable for LIDAR applications. A nanoscale VCSEP design facilitates a sub-wavelength spacing between individual phase shifters, yielding an expanded field of view and side lobes suppression. The proposed design includes a highly doped sub-micron silicon pillar covered by a thin layer of nonlinear material and an additional conductive metal layer. Characterization of a single VCSEP demonstrated a Free Spectral Range (FSR) of 53.28 ± 2.5 nm and a transmission variation of 3 dB, with V π L equal to 0.075 V-mm.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Interpretable inverse-designed cavity for on-chip nonlinear photon pair generation

Inverse design is a powerful tool in wave physics for compact, high-performance devices. To date, applications in photonics have mostly been limited to linear systems and it has rarely been investigated or demonstrated in the nonlinear regime. In addition, the “black box” nature of inverse design techniques has hindered the understanding of optimized inverse-designed structures. We propose an inverse design method with interpretable results to enhance the efficiency of on-chip photon generation rate through nonlinear processes by controlling the effective phase-matching conditions. We fabricate and characterize a compact, inverse-designed device using a silicon-on-insulator platform that allows a spontaneous four-wave mixing process to generate photon pairs at a rate of 1.1 MHz with a coincidence to accidental ratio of 162. Our design method accounts for fabrication constraints and can be used for scalable quantum light sources in large-scale communication and computing applications.

42 ENGINEERING↗
DOE OSTI2023

Through thick and thin: how optical cavities control spin

When light interacts with matter by means of scattering and absorption, we observe the resulting color. Light also probes the symmetry of matter and the result is encoded in its polarization. In the special case of circularly-polarized light, which is especially relevant in nonlinear optics, quantum photonics, and physical chemistry, a critical dimension of symmetry is along the longitudinal direction. We examine recent advances in controlling circularly-polarized light and reveal that the commonality in these advances is in judicious control of longitudinal symmetry. In particular, in the use of high quality-factor modes in dielectric metasurfaces, the finite thickness can be used to tune the modal profile. These symmetry considerations can be applied in multiplexed optical communication schemes, deterministic control of quantum emitters, and sensitive detection of the asymmetry of small molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Improving Magnetic Materials for RCS Cavity Tuners

Within the Lab Directed R&D Program at Fermilab, and in partnership with National Magnetics, we have recently begun to study and attempt to improve the loss parameter in garnet material. This could be used for fast tuner applications such as in rapid cycling synchrotrons.

Madrak, Robyn Leigh↗
DOE OSTI2021

Computer Vision Techniques Used to Monitor the Alignment of Cavities and Solenoids in the PIP-II Prototype SSR1 Cryomodule

The alignment of the SRF PIP-II string components is studied as the acceptable beam deflection, offset and defocusing, which may otherwise cause beam loss. Simulations and measurements established that the maximum deviation of the beam pipe from the reference orbit should not exceed a small fraction of the beam aperture. To observe the translations and rotations of each single component within the cryomodule, optical instruments (H-BCAM) surveying highly reflective targets, installed in the internal assembly of the module were used. The alignment monitoring concept for the PIP II SSR1 prototype cryomodule, along with relevant measurements of the components’ position monitoring during coldmass cooldown is presented in this contribution. This development paves the way to new computer vision applications in the field of cryomodule assemblies in cleanroom environment, in which robotically-assisted operations have the potential to dramatically reduce the risk of chemical and particulate contamination.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

PRELIMINARY RESULTS OF MAGNETIC AND TEMPERATURE MAP SYSTEM FOR 3 GHz SUPERCONDUCTING RADIO FREQUENCY CAVITIES

Su­per­con­duct­ing radio fre­quency (SRF) cav­i­ties are fun­da­men­tal build­ing blocks of mod­ern par­ti­cle ac­cel­er­a­tors. A sur­face re­sis­tance in the tens of nanoOhm range is achieved when cool­ing these cav­i­ties to liq­uid he­lium tem­per­a­ture, ~2 - 4 K. One of the lead­ing sources of resid­ual losses in SRF cav­i­ties is trapped mag­netic flux. Flux trap­ping mech­a­nism de­pends on dif­fer­ent sur­face prepa­ra­tions and cool-down con­di­tions. We have de­signed, de­vel­oped and com­mis­sioned a com­bined mag­netic and tem­per­a­ture map­ping sys­tem using anisotropic mag­neto-re­sis­tance sen­sors and car­bon re­sis­tors, re­spec­tively, to study the flux trap mech­a­nism in 3 GHz sin­gle-cell nio­bium cav­i­ties. In this con­tri­bu­tion, we will de­scribe the ex­per­i­men­tal ap­pa­ra­tus and pre­sent pre­lim­i­nary test re­sults.

Parajuli, I. P.↗
DOE OSTI2022

Real-Time Cavity Fault Prediction in CEBAF Using Deep Learning

Data-dri­ven pre­dic­tion of fu­ture faults is a major re­search area for many in­dus­trial ap­pli­ca­tions. In this work, we pre­sent a new pro­ce­dure of real-time fault pre­dic­tion for su­per­con­duct­ing ra­dio-fre­quency (SRF) cav­i­ties at the Con­tin­u­ous Elec­tron Beam Ac­cel­er­a­tor Fa­cil­ity (CEBAF) using deep learn­ing. CEBAF has been af­flicted by fre­quent down­time caused by SRF cav­ity faults. We per­form fault pre­dic­tion using pre-fault RF sig­nals from C100-type cry­omod­ules. Using the pre-fault sig­nal in­for­ma­tion, the new al­go­rithm pre­dicts the type of cav­ity fault be­fore the ac­tual onset. The early pre­dic­tion may en­able po­ten­tial mit­i­ga­tion strate­gies to pre­vent the fault. In our work, we apply a two-stage fault pre­dic­tion pipeline. In the first stage, a model dis­tin­guishes be­tween faulty and nor­mal sig­nals using a U-Net deep learn­ing ar­chi­tec­ture. In the sec­ond stage of the net­work, sig­nals flagged as faulty by the first model are clas­si­fied into one of seven fault types based on learned sig­na­tures in the data. Ini­tial re­sults show that our model can suc­cess­fully pre­dict most fault types 200 ms be­fore onset. We will dis­cuss rea­sons for poor model per­for­mance on spe­cific fault types.

Rahman, M.↗
DOE OSTI2022

Status of SNS Proton Power Upgrade SRF Cavities Production Qualification

The Pro­ton Power Up­grade pro­ject at Oak Ridge Na­tional Lab’s Spal­la­tion Neu­tron Source (SNS PPU) cur­rently being con­structed will dou­ble the pro­ton beam power from 1.4 to 2.8 MW by adding 7 ad­di­tional cry­omod­ules, each con­tains four six-cell high beta (\beta = 0.81) su­per­con­duct­ing radio fre­quency cav­i­ties. The cav­i­ties were built by Re­search In­stru­ments, Ger­many, with all the cav­ity pro­cess­ing done at the ven­dor site, in­clud­ing elec­trop­o­l­ish­ing as the final ac­tive chem­istry step. All 28 cav­i­ties needed for 7 cry­omod­ules were de­liv­ered to Jef­fer­son Lab, ready to be tested. The cryo­genic RF qual­i­fi­ca­tions and he­lium ves­sel weld­ing were done at Jef­fer­son Lab. The per­for­mance largely ex­ceed the re­quire­ments, and greatly ex­ceeded the per­for­mance of the orig­i­nal SNS cav­ity pro­duc­tion se­ries. Here, we pre­sent the sum­mary of RF test on pro­duc­tion cav­i­ties to this date.

Dhakal, P.↗
DOE OSTI2022

In Situ Plasma Processing of Superconducting Cavities at Jefferson Lab

Jef­fer­son Lab began a plasma pro­cess­ing pro­gram start­ing in the spring of 2019. Plasma pro­cess­ing is a com­mon tech­nique for re­mov­ing hy­dro­car­bons from sur­faces, which in­creases the work func­tion and re­duces the sec­ondary emis­sion co­ef­fi­cient. Un­like he­lium pro­cess­ing which re­lies on ion bom­bard­ment of the field emit­ters, plasma pro­cess­ing uses free oxy­gen pro­duced in the plasma to break down the hy­dro­car­bons on the sur­face of the cav­ity. The resid­u­als of the hy­dro­car­bons in the form of water, car­bon monox­ide and car­bon diox­ide are re­moved from the cry­omod­ule as part of the process gas flow. The ini­tial focus of the ef­fort is pro­cess­ing C100 cav­i­ties by in­ject­ing RF power into the HOM cou­pler ports. We will then start in­ves­ti­gat­ing pro­cess­ing of C50 cav­i­ties by in­tro­duc­ing RF into the fun­da­men­tal power cou­pler. The plan is to start pro­cess­ing cry­omod­ules in the CEBAF tun­nel in the mid-term fu­ture, with a goal of im­prov­ing the op­er­a­tional gra­di­ents and the en­ergy mar­gin of the linacs. This work will de­scribe the sys­tems and meth­ods used at JLAB for pro­cess­ing cav­i­ties using an argon oxy­gen gas mix­ture. Be­fore and after plasma pro­cess­ing re­sults will also be pre­sented.

Powers, T.↗
DOE OSTI2020

SRF Cavity R&D - Enabling New Frontiers in High Energy Physics and Quantum Science

Advances in SRF research at Fermilab have potential for impact in a wide variety of scientific fields: High energy physics (e.g. PIP-II, proposed colliders), basic energy sciences (e.g. LCLS-II, LCLS-II HE), nuclear physics (e.g. proposed MaRIE, EIC), Quantum Science (see quantum lab for details), dark matter searches (e.g. ADMX g-2), and industrial particle accelerators for wastewater treatment, cancer treatment, isotope production, and more.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Analyzing Custom Proof Masses and Quantum Limits of a Manufacturable Cavity Optical Levitation Solution

This report details results of a one-year LDRD to understand the dynamics, figures of merit, and fabrication possibilities for levitating a micro-scale, disk-shaped dielectric in an optical field. Important metrics are the stability, positional uncertainty, and required optical power to maintain levitation. Much of the results are contained in a publication written by our academic alliance collaborators. Initial structures were grown at Sandia labs and a test fabrication flow was executed. Owing to our strength in VCSEL lasers, we were particularly interested in calculations and fabrication flows that could be compatible with a VCSEL light source.

42 ENGINEERING↗
DOE OSTI2022

Optimization of a traveling wave superconducting radiofrequency cavity for upgrading the International Linear Collider

The standing wave TESLA niobium-based superconducting radio frequency structure is limited to an accelerating gradient of about 50 MV/m by the critical rf magnetic field. To break through this barrier, we explore the option of niobium-based traveling wave (TW) structures. Optimization of TW structures was done considering experimentally known limiting electric and magnetic fields. It is shown that a TW structure can have an accelerating gradient above 70 MeV/m that is about 1.5 times higher than contemporary standing wave structures with the same critical magnetic field. The other benefit of TW structures shown is R/Q about 2 times higher than the TESLA structure that reduces the dynamic heat load by a factor of 2. A method is proposed how to make TW structures multipactor-free. Some design proposals are offered to facilitate fabrication. Further increase of the real-estate gradient (equivalent to 80 MV/m active gradient) is also possible by increasing the length of the accelerating structure because of higher group velocity and cell-to-cell coupling. Realization of this work opens paths to International Linear Collider energy upgrades beyond 1 to 3 TeV in competition with CLIC. The paper will discuss corresponding opportunities and challenges.

43 PARTICLE ACCELERATORS↗