Study of MgB 2 Thin Films on Nb by Pulse Laser Deposition S.Mitsunobu, S.Inagaki, H.Nakanishi, M.Wake and M.Fukutomi* KEK,NIMR*
Scope of talk Introduction Forming method Mgb2 thin film PLD equipment PLD equipment Precursor annealing Precursor annealing RF Measurement of the MgB2 thin film and Nb Measurement of photo electron from the MgB2 thin film and Nb Summary
INTRODUCTION The large efforts have been concentrated on Nb cavities for International Linear Collider (ILC). The maximum accelerating field gradient of Nb cavities is limited about 50 MV/m due to Hcsh. MgB2 have higher Tc than Nb and expected to have higher Hcsh. Thin films of MgB2 on Nb is useful to increase future ILC energy upgrading. At KEK, the preliminary test of thin films on Nb by Pulse Laser Deposition(PLD) method have been started and initially the direct deposition of MgB2 film on Nb was studied.
Conceptual Drawing of Pulse Laser Deposition
Laser system of PLD
Vacuum Chamber of PLD
MgB2 Target Substrate
PLD Processing
Heating 620 o C in 1atom Ar
MgB2 film directly formed on Nb of 2.5mm thick
Heating 620 o C
Q measurement system
Cu Cold test cavity
Q measurement system
Photo electron measurement by PLD system
NbMgB2 film on Nb Relative Intensity of Photo electron by 284nm laser wave length
Summery MgB2 precursor films formed on Nb by PLD. The precursor film annealed at 620 o C. Cold RF measurement have been done. The film partially superconducting. Preliminary, photo electrons were measured for Nb and MgB2. Some damaging of MgB2 surface was induced by defocused laser beam. More study will be continued.