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Title: Static Magnetic Properties of AL800 Garnet Material

Abstract

A second harmonic tunable RF cavity is being devel-oped for the Fermilab Booster. This device, which prom-ises reduction of the particle beam loss at the injection, transition, and extraction stages, employs perpendicularly biased garnet material for frequency tuning. The required range of the tuning is significantly wider than in previously built and tested tunable RF devices. As a result, the mag-netic field in the garnet comes fairly close to the gyromag-netic resonance line at the lower end of the frequency range. The chosen design concept of a tuner for the cavity cannot ensure uniform magnetic field in the garnet mate-rial; thus, it is important to know the static magnetic prop-erties of the material to avoid significant increase in the lo-cal RF loss power density. This report summarizes studies performed at Fermilab to understand variations in the mag-netic properties of the AL800 garnet material used to build the tuner of the cavity.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Fermilab
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1366524
Report Number(s):
FERMILAB-CONF-17-165-AD-TD
1607488
DOE Contract Number:
AC02-07CH11359
Resource Type:
Conference
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Kuharik, J., Madrak, R., Makarov, A., Pellico, W., Sun, S., Tan, C. Y., and Terechkine, I.. Static Magnetic Properties of AL800 Garnet Material. United States: N. p., 2017. Web.
Kuharik, J., Madrak, R., Makarov, A., Pellico, W., Sun, S., Tan, C. Y., & Terechkine, I.. Static Magnetic Properties of AL800 Garnet Material. United States.
Kuharik, J., Madrak, R., Makarov, A., Pellico, W., Sun, S., Tan, C. Y., and Terechkine, I.. 2017. "Static Magnetic Properties of AL800 Garnet Material". United States. doi:. https://www.osti.gov/servlets/purl/1366524.
@article{osti_1366524,
title = {Static Magnetic Properties of AL800 Garnet Material},
author = {Kuharik, J. and Madrak, R. and Makarov, A. and Pellico, W. and Sun, S. and Tan, C. Y. and Terechkine, I.},
abstractNote = {A second harmonic tunable RF cavity is being devel-oped for the Fermilab Booster. This device, which prom-ises reduction of the particle beam loss at the injection, transition, and extraction stages, employs perpendicularly biased garnet material for frequency tuning. The required range of the tuning is significantly wider than in previously built and tested tunable RF devices. As a result, the mag-netic field in the garnet comes fairly close to the gyromag-netic resonance line at the lower end of the frequency range. The chosen design concept of a tuner for the cavity cannot ensure uniform magnetic field in the garnet mate-rial; thus, it is important to know the static magnetic prop-erties of the material to avoid significant increase in the lo-cal RF loss power density. This report summarizes studies performed at Fermilab to understand variations in the mag-netic properties of the AL800 garnet material used to build the tuner of the cavity.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 5
}

Conference:
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  • The static and dynamic properties of magnetic bubble domains in garnet films of nominal composition Y/sub 1/./sub 9/Sm/sub 0/./sub 1/Ca/sub 1/Fe/sub 4/Ge/sub 1/O/sub 12/ grown by the LPE method on GGG substrates have been measured. The films supported 5--8 ..mu..m bubbles and collapse fields ranged from 60 to 110 Oe. The temperature coefficient ..cap alpha../sub bc/ of the collapse field became more negative with increasing T/sub C/; at T/sub C/ = 468/sup 0/K, ..cap alpha../sub bc/ = -0.11 percent//sup 0/C at 50/sup 0/C and parallel ..cap alpha../sub bc/ parallel increased by approximately 8.4 percent for a 1/sup 0/K increase inmore » T/sub C/. Pulsed field gradient bubble velocity measurements were made on films as grown and after ion implantation with 2.5 x 10/sup 14/ Ne cm/sup -2/ at 100 keV energy. In almost all cases, bubbles having rotation number n/sub r/ = 1 were observed in ion-implanted films and n/sub r/ = 0 bubbles were seen in as-grown samples. There was little evidence of dynamic conversion for V less than V/sub p/ for repetitive measurements with a given bubble. However, for randomly selected bubbles there was greater scatter in velocity. Mobility values for drive fields less than or equal to 4.5 Oe ranged from about 1100 to 1400 cm s/sup -1/ Oe/sup -1/ withthe dynamic coercive force always less than 0.6 Oe.« less
  • Over 300 garnet films of nominal composition (Y/sub 1/./sub 5/Sm/sub 0/./sub 3/Lu/sub 0/./sub 3/Ca/sub 0/./sub 9/)(Fe/sub 4/./sub 1/Ge/sub 0/./sub 9/)O/sub 12/ were prepared for 5 ..mu..m bubble device operation at 0.5 MHz from -25 to 75/sup 0/C. Melt composition, run-to-run process control, as well as temperature and composition differentials required for reproducible growth are presented. The effects of charge imbalance and mobility changes on domain coercivity are discussed. The static bubble properties were measured from -30 to 100/sup 0/C, and temperature coefficients of -0.2 percent//sup 0/C and -0.1 percent//sup 0/C were found for the bubble collapse field and material length,more » respectively. With domain wall coercivity as low as 0.1 Oe at 25/sup 0/C and 0.4 Oe at -25/sup 0/C and with q > 4 at 75/sup 0/C, this material should be well suited for devices requiring moderate speed of operation over broad ranges of temperature.« less
  • A perpendicularly biased 2nd harmonic cavity is being designed and built for the Fermilab Booster, to help with injection and extraction. Tunable accelerating cavities were previously designed and prototyped at LANL, TRIUMF, and SSCL for use at 45-60 MHz (LANL at 50-84 MHz). The required frequency range for FNAL is 76 - 106 MHz. The garnet material chosen for the tuner is AL-800. To reliably model the cavity, its static permeability and loss tangent must be well known. As this information is not supplied by the vendor or in publications of previous studies, a first order evaluation of these propertiesmore » was made using material samples. This paper summarizes the results of the corresponding measurements« less
  • Pulsed laser deposition has been used to grow thin (10–84 nm) epitaxial layers of Yttrium Iron Garnet Y{sub 3}Fe{sub 5}O{sub 12} (YIG) on (111)–oriented Gadolinium Gallium Garnet substrates at different growth conditions. Atomic force microscopy showed flat surface morphology both on micrometer and nanometer scales. X-ray diffraction measurements revealed that the films are coherent with the substrate in the interface plane. The interplane distance in the [111] direction was found to be by 1.2% larger than expected for YIG stoichiometric pseudomorphic film indicating presence of rhombohedral distortion in this direction. Polar Kerr effect and ferromagnetic resonance measurements showed existence of additionalmore » magnetic anisotropy, which adds to the demagnetizing field to keep magnetization vector in the film plane. The origin of the magnetic anisotropy is related to the strain in YIG films observed by XRD. Magneto-optical Kerr effect measurements revealed important role of magnetization rotation during magnetization reversal. An unusual fine structure of microwave magnetic resonance spectra has been observed in the film grown at reduced (0.5 mTorr) oxygen pressure. Surface spin wave propagation has been demonstrated in the in-plane magnetized films.« less
  • Simulated transient tests and standard static mechanical property tests were performed on irradiated specimens of D9, a low-swelling, advanced austenitic stainless steel developed for fast reactor operation. Results of the transient tests were compared with existing data on 316 and HT9 stainless steels. The D9 alloys exhibited the same behavior attributed the fuel adjacency effect (which is characterized by reduced strength and ductility as a result of cladding contact with oxide fuel) observed in 316 stainless steel. In the mechanical property tensile and fracture toughness tests, D9 exhibited a slightly lower fracture toughness than either HT9 or 316 stainless steel.more » Comparison of tensile strengths indicated that irradiated D9 is stronger than HT9, but slightly weaker than 316 stainless steel. The D9 alloy exhibited a lower tensile ductility than either 316 stainless steel or HT9. The D9 transient and mechanical properties data are now available for computer code analysis of D9 as a fast reactor fuel system material. 15 refs., 12 figs.« less