STATUS OF KEK STUDIES OF SUPERCONDUCTING THIN FILMS BY  PULSED LASER DEPOSITION    S. Mitsunobu , S. Inagaki, H. Nakanishi...
PLD Thin Film Superconductor at KEK <ul><li>TE 011  Mode Cavity </li></ul><ul><li>Nb Thin Film on Nb, Sapphire </li></ul><...
 
Conceptual Drawing of Pulse Laser Deposition
Laser system of PLD
Vacuum Chamber of PLD
PLD Processing
TE 011  Mode Cavity
Nb 3 Sn on Nb Nb on Nb Nb on Sapphire
Nb film on Sapphire Al 2 O 3 Nb Nb 2 O 5
Nb thin film on sapphire have low Q value of less than 100. TE011 peak was not observed. TE 011
Nb thin film on Nb substrata Nb Nb 2 O 5 Nb Nb 2 O 5
Surface resistance of Nb thin film on Nb
Nb 3 Sn thin film show no superconducting transition around  18K. 10 4
MgB 2   <ul><li>We have been engaged in fabrication of high-Tc or MgB  thin films on metallic substrates. At the internati...
PRECURSOR   POST-ANNEALING   METHOD <ul><li>After assembling the cavity with the component parts, we deposit MgB on the in...
RF Measurments of MgB 2  ON Nb and Ti
 
TM010 mode cavity  <ul><li>Nb TM010 cavity made from Nb rod. </li></ul><ul><li>Each half cell inner surfaces were formed M...
TM010 cavity
Laser Mover Camera Mirror Vacuum Chamber Side View Top View Mover Mirror Camera Laser PC (python+PyVISA+Tkinter) GPIB Targ...
 
Q-value of the cavity fabricated with process (pi).
Microwave surface resistance  of a quadrant.
SUMMARY <ul><li>We are making MgB2 films by a precursor post-annealing </li></ul><ul><li>method on copper and Nb cavities ...
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Mitsunobu - Status of KEK Studies of Superconducting Thin Films by Pulsed Laser Deposition

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Status of KEK studies on MgB2 (Shinji Mitsunobu - 20')
Speaker: Shinji Mitsunobu - KEK | Duration: 20 min.
Abstract
We have been engaged in fabrication of high-Tc or MgB thin films on
metallic substrates. At the international workshop on thin films in
Padova, we showed our basic idea to make an accelerating-mode cavity.
In the last of this paper, we report a subsequent development, mainly a
partial success in fabricating superconducting film on a quadrant
cavity of an accelerator structure. In the beginning, we describe some
results concerning fabrication of films on Niobium and Titanium
surfaces.
Studies of Nb and Nb3Sn thin films by PLD will be shown.

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Mitsunobu - Status of KEK Studies of Superconducting Thin Films by Pulsed Laser Deposition

  1. 1. STATUS OF KEK STUDIES OF SUPERCONDUCTING THIN FILMS BY PULSED LASER DEPOSITION   S. Mitsunobu , S. Inagaki, H. Nakanishi, K. Saito, T. Takatomi, M. Wake, and M. Yoshida High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan M. Fukutomi, National Institute for Material Science (NIMS) , Tsukuba, Ibaraki, Japan
  2. 2. PLD Thin Film Superconductor at KEK <ul><li>TE 011 Mode Cavity </li></ul><ul><li>Nb Thin Film on Nb, Sapphire </li></ul><ul><li>Nb 3 Sn Thin Film on Nb </li></ul><ul><li>MgB 2 Thin Film on Nb, Ti, Cu </li></ul><ul><li>TM 010 Mode Cavity </li></ul><ul><li>MgB 2 Thin Film on Nb, Cu and Cu Quadrant Cavity </li></ul>
  3. 4. Conceptual Drawing of Pulse Laser Deposition
  4. 5. Laser system of PLD
  5. 6. Vacuum Chamber of PLD
  6. 7. PLD Processing
  7. 8. TE 011 Mode Cavity
  8. 9. Nb 3 Sn on Nb Nb on Nb Nb on Sapphire
  9. 10. Nb film on Sapphire Al 2 O 3 Nb Nb 2 O 5
  10. 11. Nb thin film on sapphire have low Q value of less than 100. TE011 peak was not observed. TE 011
  11. 12. Nb thin film on Nb substrata Nb Nb 2 O 5 Nb Nb 2 O 5
  12. 13. Surface resistance of Nb thin film on Nb
  13. 14. Nb 3 Sn thin film show no superconducting transition around 18K. 10 4
  14. 15. MgB 2 <ul><li>We have been engaged in fabrication of high-Tc or MgB thin films on metallic substrates. At the international workshop on thin films in Padova, we showed our basic idea to make an accelerating-mode cavity. In the last of this paper, we report a subsequent development, mainly a partial success in fabricating superconducting film on a quadrant cavity of an accelerator structure. In the beginning, we describe some results concerning fabrication of films on Niobium and Titanium surfaces. </li></ul>
  15. 16. PRECURSOR POST-ANNEALING METHOD <ul><li>After assembling the cavity with the component parts, we deposit MgB on the inner surface by pulsed laser deposition (PLD) and heat up to temperatures around 600 o C.This procedure is called precursor post-annealing method. </li></ul><ul><li>This method consists of two steps. </li></ul><ul><li>(i) The target is a pellet with a mixture of MgB 2 and Mg </li></ul><ul><li>powder with the stoichiometry ofMg:B=2:1. Excimer laser with  = 248 nm (KrF), 400 mJ, and 5–10 Hz is irrradiated </li></ul><ul><li>on the target in 6x10 -5 Torr Ar atmosphere at room temperature for 2 hr. The thickness of the fabricated film is around 1  m. </li></ul><ul><li>(ii) Typically, the precursors are heated in 1 atm Ar gas at 550–650 o C for 10 min. This process must be optimized so that magnesium evaporation should be well controlled to become MgB 2 in the phase diagram . </li></ul><ul><li>In the preceding experiments, we deposited chromium on the copper surface, then yttria-stabilized-zirconia (YSZ), and MgB 2 . However, we now know that if the copper oxide is completely removed from the surface, the chromium buffer layer can be omissible. </li></ul><ul><li>Two parts machined vertical to the axis are assembled to make a cavity. The inside surface is to be covered with MgB 2 films. </li></ul>
  16. 17. RF Measurments of MgB 2 ON Nb and Ti
  17. 19. TM010 mode cavity <ul><li>Nb TM010 cavity made from Nb rod. </li></ul><ul><li>Each half cell inner surfaces were formed MgB2 precursor films by PLD. </li></ul><ul><li>The half cell joint by bolts. </li></ul><ul><li>The equator part was formed by conical target. </li></ul><ul><li>The cavity was heated by cylindrical heater upto 620 digC. </li></ul>
  18. 20. TM010 cavity
  19. 21. Laser Mover Camera Mirror Vacuum Chamber Side View Top View Mover Mirror Camera Laser PC (python+PyVISA+Tkinter) GPIB Target Cone Shape MgB 2 Target Disc Shape MgB 2 Target Rotation Horizontal Vertical
  20. 23. Q-value of the cavity fabricated with process (pi).
  21. 24. Microwave surface resistance of a quadrant.
  22. 25. SUMMARY <ul><li>We are making MgB2 films by a precursor post-annealing </li></ul><ul><li>method on copper and Nb cavities of an accelerator structure. </li></ul><ul><li>Some of them have already showed superconducting </li></ul><ul><li>properties. </li></ul><ul><li>We concentrate our effort to find the better condition </li></ul><ul><li>to get films of better quality. We hope we can make a high power test in future. </li></ul><ul><li>MgB2 thin films on Nb disks show partial shielding effect which is important for high field cavity. </li></ul><ul><li>Nb and Nb3Sn PLD films study started. </li></ul>
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