A Superconducting Permeameter for Characterizing Soft Magnetic Materials at High Fields

Asuperconductingpermeameterisproposedtocharacterizethemagneticpropertiesofhigh-energysuperconducting magnet yokes at their operating temperatureand saturation level. The main problem of superconductingcoils, an undesired quench, was faced by specific protectionsimulations, which has led to a self-protected system. Thesuperconducting permeameter was used to perform the magneticcharacterization of ARMCO Pure Iron, the material for the newHigh-Luminosity Large Hadron Collider (HL-LHC) supercon-ducting magnet yokes, which was performed at the cryogenictemperature of 4.2 K and a saturation level of nearly 3 T.Two case studies based on the new HL-LHC superconductingquadrupole and dipole magnets highlight the impact of themagnetic properties of the yoke on the performance of thesuperconducting magnets, showing that the common assumptionthat heavily saturated steels with similar chemical compositionbehave precisely the same way has been proven wrong

Modeling, simulation and measurement of ferrite core loss in frequency range up to 1GHz

U radu je predložena modifikovana vatmetarska metoda za merenje snage gubitaka u toroidnim feritnim jezgrima koja je prilagođena osciloskopima male ulazne impedanse. Metoda je verifikovana na komercijalnim uzorcima od Mn-Zn i Ni-Zn feritnih materijala. Metoda je upotrebljena za merenje kompleksne permeabilnosti i gustine snage gubitaka dodatno obrađenih komercijalnih Mn-Zn feritnih prahova. Utvrđeno je da se dodatnim tehnološkim procesima (mlevenjem i prosejavanjem) početnog komercijanog praha mogu napraviti feritna jezgra manje gustine snage gubitaka i veće permeabilnosti.The thesis proposes a modified Watt-meter method for measuring core loss of ferrite cores, which is adjusted to oscilloscopes with the small input impedance. The method is verified on comercial Mn-Zn and Ni-Zn ring cores. The method is used to measure the influence of starting powder sieving and milling on the core loss density and permeability of Mn-Zn ferrite. The experimental results and calculations show the significance of the additional milling and sieving process on magnetic properties of Mn-Zn ferrite in the frequency range from 0.1MHz to 10MHz. These processes increase the relative permeability about 3 times and decrease the core loss 4 times by milling of the starting powder