Dr. Yonglin Ju: Professional experience

Columbia University's Department of Physics Nevis Laboratories 136 South Broadway, P. O. Box 137, Irvington, NY 10533 Phone: 914-591-2802, Fax: 914-591-8120 e-mail: ju@nevis.columbia.edu

Professional Experience

• 10/2002~present Research Scientist
  Nevis Laboratories, Department of Physics, Columbia University, New York 10027, USA
  • Study, design and develop new electron bubble particle detectors for the detection of low-energy particles from natural sources such as the Sun and supernovae, and Neutrinos from accelerator beams and nuclear reactors, for the next generation of colliding-beam facilities
  • Construct and perform test on electron bubble chamber by using cryogenic liquids (Helium, Neon and hydrogen) as the detecting medium, and determine the feasibility of the construction of a modest-size tracking chmaber that in turn lead to a study for a large particle detectors for neutrinos and other particle physics applications
  
  
• 10/2000~10/2002 Research Professor
  Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100080, China
  • Led, designed and constructed 4K multi-stage pulse tube refrigerators (PTRs) for cryogen-free operation of superconducting magnets (dry-cooling magnets), including hardware and software design, lab facilities development, experimental test and measurements
  • Led, proposed and performed studies on non-metallic non-magnetic miniature cryocoolers for low-noise continuous cooling of highly sensitive high-Tc SQUIDs
  • Developed 2W/60K medium-size low power pulse tube cryocoolers (PTCs) for cooling HTS RF filter subsystem in ground base stations for wireless telecommunications
  • Proposed and performed heat transfer enhancement of cryogenic regenerators (reverse flow heat exchangers) subjected to oscillating flows
  • Led, proposed and conducted investigations on performance analysis and structure optimization of micro-scale cryogenic heat pipes at liquid nitrogen temperatures
  • Directed and supervised graduate student thesis in MS and Ph.D. level
  
  
• 10/1998 ~10/2000 Post-doc Research Associate
  Group of Low Temperature Physics, Department of Applied Physics, Eindhoven University of Technology, Eindhoven 5600MB, the Netherlands
  • Investigated multi-stage PTRs operated at liquid helium temperatures, including hardware and software design, experimental test and measurements. A world-record lowest temperature of 1.78K (lower than the lambda transition of 4He) was achieved by using 3He as working fluid with a three-stage PTR (Co-work, with Dr. M. Y. Xu)
  • Developed a comprehensive CFD model (with mixed Eulerian-Lagrangian methods) and a computer code, performed numerical analysis for simulating time-variations of dynamic parameters and visualizing the cooling-down processes of 4K-PTRs
  • Performed thermodynamic analyses on GM-type PTRs and rotary valves, and general expressions of the COP have been derived out and discussed
  • Performed pulse tube performance at very low temperatures
  
  
• 07/1998 ~10/1998 Assistant Professor
  Cryogenic Laboratory, Chinese Academy of Sciences, Beijing 100080, China
  • Performed thermal analysis for predicting transient temperature distributions in the freezing process and thermal treatment of biological tissue in cryosurgery
  • Conducted researches on oscillating flow behavior and heat transfer characteristics of regenerators (compact heat exchangers) in pulse tube cryocoolers
  • Proposed research projects and supervised graduate student thesis in MS level
  
  
• 09/1995 ~06/1998 Ph.D. Candidate & Research Assistant
  Cryogenic Laboratory and Technical Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080, China
  • Designed and built a dynamic experimental set-up with computer controlled fully automated measuring system for PTCs and regenerators.
  • Conducted and performed experimental investigations on oscillating flow characteristics of PTCs. DC-gas flow was first observed in the PTCs and evaluated from experimental measurements. Effects of double-inlet and multi-bypass versions on the refrigeration performance and flow mechanism of PTCs were clarified
  • Performed experiments and theoretical analysis on the oscillating flow characteristics (pressure drop and phase shift) for the high frequency regenerators
  • Developed a CFD model and a computer code and performed numerical analysis for the PTCs, and further developed into a design and optimization tool for regenerative cryogenic cryocoolers, which has been accepted and now being used by Pulse Tube Group of CL/CAS
  
  
• 02/1995 ~08/1995 Research Assistant
  Cryogenic Laboratory, Chinese Academy of Sciences, Beijing 100080, China
  • Investigated experimentally two-stage pulse tube refrigerators, including software and hardware design, experimental test and measurements. A low temperature of 11K was obtained
  
  
• 09/1992 ~02/1995 MS Candidate & Research Assistant
  School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China
  • Designed and constructed an experimental set-up for melting and solidification heat transfer, and developed a data acquisition system and codes for data reduction and graphics
  • Investigated and visualized melting and solidification heat transfer in a rectangular enclosure with discrete protruding heat sources on one of its vertical wall
  • Developed a CFD model and performed thermal analysis on natural heat transfer within an enclosure with discrete heat sources for quantitative comparison with benchmark and references

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