Measurements of Electromagnetic Properties of Ferrites above Curie Temperature and impact on kicker performance

Transcription

1 Measurements of Electromagnetic Properties of Ferrites above Curie Temperature and impact on kicker performance Agnieszka Chmielińska École Polytechnique Fédérale de Lausanne CERN TE ABT PPE April 6, 2018 Agnieszka Chmielińska Impedance Meeting / 34

2 Introduction Motivation EM material characterization techniques 1 Motivation for these studies 2 EM material characterization techniques 3 4 Implications 5 Agnieszka Chmielińska Impedance Meeting / 34

3 Motivation Introduction Motivation EM material characterization techniques. 1 Interaction of the beam with the resistive part of the longitudinal beam coupling impedance leads to power dissipation and heating of different elements in the accelerator ring. 2 In particular, power deposition in the kicker magnets can be a practical limitation: if the temperature of the ferrite yoke exceeds the Curie temperature, the beam will not be properly deflected. 3 In addition, imaginary component of beam coupling impedance leads to beam instability. The knowledge of EM properties of materials in a GHz frequency range is important for a correct impedance evaluation. Parameters of interest: µ = µ + jµ, ε = ε + jε Temperature dependence of the material electromagnetic properties may have impact on kicker performance Agnieszka Chmielińska Impedance Meeting / 34

4 Ferrite types considered Introduction Motivation EM material characterization techniques CMD5005: - fast field response, negligible eddy-currents, acceptable outgassing - limitation: relatively low Curie temperature ( 125 C) CMD10: - increased Curie temperature ( 225 C) - limited initial permeability µ r for required field strength and homogenity CMD10B: - blended ferrite (50% CMD5005 & 50% CMD10) - increased Curie temperature ( 190 C) - acceptable relative permeability. Considered for LHC MKI ferrite yoke replacement. Ordered for prototype SPS MKP kicker magnet. Supplier data: Agnieszka Chmielińska Impedance Meeting / 34

5 Motivation EM material characterization techniques EM material characterization techniques EM properties of the linear, homogeneous, isotropic medium can be determined using transmission line methods of material characterization. A sample of the material is mounted inside a TEM-mode test fixture and an attached network analyzer measures the scattering parameters. Important condition: the cross section of the line is expected to be completely and homogeneously filled with the material to avoid measurement errors due to the air gaps. Dedicated methods are used to extract material properties from the scattering data, i.e. developed by W. Barry, Nicolson-Ross-Weir (NRW). Transmission line techniques can be divided into the following categories: - Off-resonance waveguide, stripline and coaxial line (2 port measurement) - Off-resonance short-circuit line (1 port measurement) - Open circuit techniques - Resonant transmission line techniques Agnieszka Chmielińska Impedance Meeting / 34

6 Motivation EM material characterization techniques Transmission/Reflection Method (W. Barry), Ref. [1] Schematic diagram: Port 1 Port 2 Z 0 Z Z 0 ' '' ' '' L 1 d L 2 Free space region: Z 0, k 0 = ω µ 0 ε 0 Important: Z 0 is matched to the VNA. Ferrite region: Z = Z µr 0, k = k ε 0 µr ε r r Reflection coefficient at the material boundaries: R = ± Z Z 0. Z+Z 0 Transmission parameter of the filled line: T = e jkd. Final expressions for ε and µ expressed in terms of R and k: ε = k ( ) 1 R k R µ = k ( ) 1 + R k 0 1 R (1) (2) can be found from measured S-parameters: ( ) e kd = cos 1 j2k 0 (L 1 +L 2 ) + S21 2 S2 11 2e jk 0(L 1 +L 2 ) S 21 (3) S 11 R = e jk 0(L 1 +L 2 ) S 21 e jkd (4) Agnieszka Chmielińska Impedance Meeting / 34

7 Short Circuit Method, Ref. [2, 3] Motivation EM material characterization techniques Schematic diagram: Port 1 SC 2left 1left 0= 1 Z Z ' '' ' '' 2right 1right Z 2 Z 1 Analysis of reflections at interfaces allows calculation of material properties numerically using Newton Raphson algorithm. L 1 d Free space region: Z 0, k 0 = ω µ 0 ε 0 Important: Z 0 is matched to the VNA. Ferrite region: characteristic impedace Z Agnieszka Chmielińska Impedance Meeting / 34

8 Experimental Setup Introduction Motivation EM material characterization techniques Photo: Ferrite samples DeziFix sample holder Electronic calibration kit Network Analyzer Bakeout power supply Temperature controller Multimeter PT100 sensor Agnieszka Chmielińska Impedance Meeting / 34

9 Introduction Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature T/R Method - Electrical Delay Measurement Sample holder: Port 1 (first half shorted) Port 2 (second half shorted) Electrical delay measured from the impulse response in time domain for both halves of the sample holder. Result: sample holder length equal to 175 mm. Agnieszka Chmielińska Impedance Meeting / 34

10 Introduction Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature Short Circuit Method - Electrical delay measurement Sample holder: S11 at Port 1 Electrical delay measured from the impulse response in time domain for one half of the sample holder in short. Result: sample holder length equal to 86.5 mm. Agnieszka Chmielińska Impedance Meeting / 34

11 : T/R measurements at 25 C. Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature Reminder: µ = µ + jµ (µ - inductive component, µ - resistive component) Relative Permeability REAL: Relative Permeability IMAG: CMD10B µ r (real) in comparison to CMD10 is higher only below 3 MHz. The imaginary part for the 3 ferrites behaves differently below 100 MHz. CMD10B is 50%/50% blend of CMD10 (T c = 250 ) and CMD5005 (T c = 125 ): measured characteristics are between those of the two ferrite types, as expected. Agnieszka Chmielińska Impedance Meeting / 34

12 : T/R measurements at 25 C. Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature Relative Permittivity REAL: Relative Permittivity IMAG: Reasonable good agreement with typically used values: ε r (12 13) for the frequencies above 400 MHz. T/R method is not accurate at high frequencies. Agnieszka Chmielińska Impedance Meeting / 34

13 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : T/R and Short Circuit measurements at 25 C. Relative Permeability (CMD5005): Relative Permeability (CMD10): Very good agreement between the two measurement methods. Very good agreement with the datasheet ( Dat ). Short circuit line method has been found to be more accurate at high frequencies. However, the maximum measured frequency is limited by the half-wavelength resonance (Ref. [1]). Agnieszka Chmielińska Impedance Meeting / 34

14 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : T/R and Short Circuit measurements at 25 C. Relative Permeability (CMD10B): Agnieszka Chmielińska Impedance Meeting / 34

15 Introduction Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit measurements at High Temperature Setup: Sample holder wrapped in aluminium foil. Temperature control: thermocouple, PT100, non-reversible stickers. Gradual increase of temp., allow 20 min for thermal equilibrium to be reached at each step (+ check on VNA). Limit of heating: 175 C - due to thermal properties of dielectric inside DeziFix. Agnieszka Chmielińska Impedance Meeting / 34

16 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit measurements at High Temperature Relative Permeability REAL (CMD5005): Relative Permeability IMAG (CMD5005): At low frequency range (to 10 MHz), permeability increases with temperature up to 125 C, while at high frequencies the opposite effect is observed. Accordingly, two mechanisms of losses can be distinguished (see Ref. [5, 6]). Above Curie temperature, both real and imaginary part drops down. In repeated measurements it has been observed that µ r (real) with low magnitude oscillates around zero at very high frequencies (this effect is not understood). Agnieszka Chmielińska Impedance Meeting / 34

17 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit measurements at High Temperature S11 (CMD5005): S11 (CMD5005): The Curie temperature has been reached during measurments: S11=0 db and ferrite becomes transparent. Agnieszka Chmielińska Impedance Meeting / 34

18 Introduction Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit measurements at High Temperature Sample holder: Non-reversible temperature indicators have been used to verify thermocouple and PT100 indications. Agnieszka Chmielińska Impedance Meeting / 34

19 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit measurements at High Temperature Relative Permeability REAL (CMD10): Relative Permeability IMAG (CMD10): The same dependencies are observed. Here, the Curie temperature was not reached. Agnieszka Chmielińska Impedance Meeting / 34

20 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit measurements at High Temperature S11 (CMD10): The same behaviour is observed. Agnieszka Chmielińska Impedance Meeting / 34

21 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit measurements at High Temperature Relative Permeability REAL (CMD10B): Relative Permeability IMAG (CMD10B): The same dependencies are observed. Again, the Curie temperature was not reached. Agnieszka Chmielińska Impedance Meeting / 34

22 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit measurements at High Temperature S11 (CMD10B): The same behaviour is observed. Agnieszka Chmielińska Impedance Meeting / 34

23 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit method - Comparison at 50 C. Relative Permeability REAL: Relative Permeability IMAG: Frequency content of the MKI current pulse up to 10 MHz. For field magnitude and homogenity of the MKI, µ r (real) above 500 is required. In beam spectrum frequency range above 200 MHz, µ r (imag) are very similar for 3 ferrites. Since the main impedance peak for LHC MKI is at 400 MHz, no significant difference in losses is expected. The ferrite temperature is expected to be lower than set temperature because of thermal conduction along the cables. Agnieszka Chmielińska Impedance Meeting / 34

24 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit method - Comparison at 100 C. Relative Permeability REAL: Relative Permeability IMAG: Agnieszka Chmielińska Impedance Meeting / 34

25 Electrical delay T/R and Short Circuit measurements at 25 C. Short Circuit measurements at High Temperature : Short Circuit method - Comparison at 150 C. Relative Permeability REAL: Relative Permeability IMAG: Agnieszka Chmielińska Impedance Meeting / 34

26 Implications Introduction 1. Performance of the yoke After a long physics fill with high intensity beam ( increased temp. of the yoke) the losses of the yoke are expected to be significanly smaller based on presented results. In particular, that would suggest that LHC MKI power loss is overestimated. Presented results might be also an input for power loss calculation for another kickers, i.e. SPS MKE and MKP. 2. Performance of EM absorbers (i.e. LHC MKI rings) On the other hand, as above, the power deposition distribution may change, since at higher temperatures the ferrite rings could not absorb the power efficiently anymore! (cooling of the rings being studied). CST LHC MKI model: Ferrite yokes Metallic cylinder Overlap length Ferrite rings Power distribution LHC MKI, Ref. [4]: Agnieszka Chmielińska Impedance Meeting / 34

27 Implications Introduction Simulation, Ref. [7]: 3. Field strength For the LHC MKI, the highest significant frequency of the current pulse is 10 MHz. From simulations, the relative permeability should be above 500 up to this frequency. However, this is not the case, when the CMD5005 is operting at higher temperatures (slide 16). 4. Homogenity of the field For the LHC MKI, the homogenity of the field stays within specification when the relative permeability is above 100 up to 10 MHz. This condition is satisfied, unless the operating temperature closely approaches T C. Simulation, Ref. [7]: Agnieszka Chmielińska Impedance Meeting / 34

28 Input Data for CST (CMD5005) Relative Permeability REAL (DATA+CST FIT): Relative Permeability REAL (DATA+CST FIT): Agnieszka Chmielińska Impedance Meeting / 34

29 Introduction 1 EM properties of ferrites (CMD5005, CMD10, CMD10B) have been characterized using transmission/reflection and short circuit method. 2 Very good agrreement between the two methods and datasheet specification has been achieved. However, short circuit method is more accurate for µ r(real) at high frequencies. 3 Temperature dependence of the permeability is governed by two mechanisms. Up to a specific frequency, permeability increases with temperature and above this frequency it drops down. 4 Above Curie temperature, real and imaginary part rapidly fall down. 5 Measurement data (µ r,ε r) can be an important input for impedance simulations and power loss predictions. Agnieszka Chmielińska Impedance Meeting / 34

30 Acknowledgements Introduction M.J. Barnes, F. Caspers, B. K. Popovic, C. Vollinger, V. Vlachodimitropoulos Agnieszka Chmielińska Impedance Meeting / 34

31 Thank you for your attention. Agnieszka Chmielińska Impedance Meeting / 34

32 References I Introduction [1] W. Barry, Ą Broad-Band, Automated, Stripline Technique for the Simultaneous Measurement of Complex Permittivity and Permeability", IEEE Transactions on Microwave Theory and Techniques, vol. 34, no. 1, p. 80, January [2] C. Vollinger, F. Caspers, E. Jensen, "Permittivity and Permeability Measurement Methods for Particle Accelerator Related Materials", in Proc. IPAC 14, Dresden, Germany, July 2014, paper THPRI054, pp [3] J. Baker-Jarvis, M. D. Janezic, J. H. Grosvenor, and R. G. Geyer, "Transmission/reflection and short-circuit line methods for measuring permittivity and permeability", NIST, Gaithersburg, MD, USA, Tech. Rep. 1355, March [4] V. Vlachodimitropoulos, M. J. Barnes, L. Ducimetière, L. Vega Cid, W. Weterings, Śtudy of an Improved Beam Screen Design for the LHC Injection Kicker Magnet for HL-LHC", in Proc. IPAC 16, Busan, Korea, May 2016, paper THPMW030, pp [5] F. Fiorillo, C. Beatrice, M. Coisson, L. Zhemchuzhna, Łoss and Permeability Dependence on Temperature in Soft Ferrites", IEEE Transactions on Magnetics, vol. 45, no. 10, p. 4242, October Agnieszka Chmielińska Impedance Meeting / 34

33 References II Introduction [6] T. Tsutaoka, T. Kasagi, T. Nakamura, K. Hatakeyama, "High Frequency Permeability of Mn-Zn Ferrite and its Composite Materials", J. Phys. IV France, vol. 7, no. C1, p. 557, March [7] M. J. Barnes, L. Ducimetière, "Vacuum, Ferrite, Cooling, Beam Impedance and Pre-Scrubbing", 3 rd MKI Strategy Meeting, CERN, Geneva, Switzerland, February 20 th, Agnieszka Chmielińska Impedance Meeting / 34

34 Spare slides (CMD10B) Introduction Relative Permeability REAL: Relative Permeability REAL (ZOOM): Agnieszka Chmielińska Impedance Meeting / 34