Robert Tjoelker

Robert L. Tjoelker was born in 1958 in Bellingham, WA. He received degrees in architecture, physics, and mathematics from the University of Washington in Seattle and the Ph.D degree in physics from Harvard University, Cambridge, MA for a precision comparison of the proton and antiproton mass. He is involved in numerous time and frequency research and development activities with interests in the development of practical high-stability mercury trapped ion frequency standards, state-of-the-art clocks and timing, and reference distribution systems. His group leads and is responsible for the JPL Frequency Standards Test Laboratory, the NASA Deep Space Network Frequency and Timing System, and frequency and timing technology development, implementation, and characterization for the Deep Space Network and spaceflight.


Education: 
  • Ph.D. in Physics, Harvard University, Cambridge, MA; November 1990
  • Dissertation: "Antiprotons in a Penning Trap: A New Measurement of the Inertial Mass"
  • M.S. in Physics, University of Washington, Seattle, WA; November 1985
  • B.S. in Physics, University of Washington, Seattle, WA; June 1984
  • B.S. in Mathematics, University of Washington, Seattle, WA; June 1984
  • B.A. Magna cum Laude, in Architecture, University of Washington, Seattle, WA; June 1980

Research Interests: 
  • Frequency and Timing: Science, Technology, Engineering, and Systems.
  • Atomic Frequency Standards and Clocks
  • Trapped Ion Frequency Standards and Mass Spectroscopy
  • Frequency and Time Metrology
  • Precision Measurements and Fundamental Atomic Physics

Professional Experience: 

NASA Jet Propulsion Laboratory (1990 - Present)

  • Technical Group Supervisor; Section 335 (1999-present)
    • Frequency & Timing Advanced Instrument Development Group
  • Frequency and Timing System Engineer, NASA Deep Space Network, (2003-present)
  • Principal Member of Technical Staff ( 2002-present)
  • ND Frequency & Timing Work Area & Task Manager (1998-present)
  • Project Element Manager, Frequency & Timing Laboratory, Section 335, (1998-1999)
  • Time and Frequency Research Staff (1990-1998) European Laboratory for Particle Physics, CERN ; Geneva, Switzerland.
  • CERN Associate Scientist, (1988-1990) Harvard University; Cambridge, MA;
  • Harvard University Traveling Scholar (1988-1990)
  • Research Assistant; Dept. of Physics (1987-1990) University of Washington; Seattle, WA;
  • Research Assistant; Dept. of Physics (1985-1987)

Selected Awards: 
  • NASA Group Achievement Award, "for Master Clock and Timing System Development Team”, 2006.
  • NASA Space Act Award, “Master Clock & Time Distribution System for the NASA Deep Space Network”, 2005.
  • IEEE Senior Member, 2005
  • NASA Space Act Award “Stabilized Reference Frequency Distribution for Radio Science with the Cassini Spacecraft and the Deep Space Network” Aug. 2004.
  • NASA Group Achievement Award, "for Cassini Radio Science Ground System Development Team", 2004.
  • NASA Space Act Award, “Multi-Purpose Time Analyzer and Monitor for Deep Space Network Time Synchronization”, 2002.
  • NASA Group Achievement Award, “for Frequency & Timing Monitor and Control Upgrade Team",2002.
  • NASA Group Achievement Award, “for exceptional contributions to the development of the linear ion trap frequency standard", 1995.
  • National Research Council NIST Fellowship, NIST, 1990.
  • Shell Fellowship, University of Washington, 1984.
  • Paul M. Higgs-Frederick A. Osborn Prize, University of Washington, 1984.

Other Affiliations:

  • Member, Executive Committee, Precise Time and Time Interval (PTTI) Applications Meeting, 1998-present.
  • Member, Technical Program Committee, International IEEE Frequency Control Symposium, 1997-2007.
  • Technical Program Chair, 2005 Joint IEEE Frequency Control Symposium & PTTI Meeting, 2005.
  • TPC Vice Chair, Group 3, 2004 Joint IEEE Frequency Control Symposium & UFFC Meeting, 2004.
  • TPC Vice Chair, Group 3, 2003 Joint IEEE Frequency Control Symposium & EFTF Meeting,2003.
  • Member, United States Study Group 7, ITU-R (International Telecommunications Union), 1997-present.
  • Member, IEEE ( Institute of Electrical and Electronics Engineers), UFFC, 1997-present.
  • Member, APS (American Physical Society), 1985-present.
  • Member, DAMOP, (Division of Atomic, Molecular, and Optical Physics), 1985-present.

Selected Publications: 
  1. E. Burt, W. Diener, R. Tjoelker, ”Long Term Measurements of JPL’s Compensated Multip-pole Linear Ion Trap Standard at the 10-16 Level”, in proceedings of the 2007 Joint IEEE Frequency Control Symposium and European Frequency and Time Forum, Geneva, Switzerland, May 2007.
  2. M. Calhoun, S. Huang, R. Tjoelker, “ Stable Photonic Links for Frequency and Time Transfer in the Deep Space Network and Antenna Arrays”, in IEEE Proceedings special issue on Deep Space Tracking, Communication, and Navigation. To be published September 2007.
  3. C. Greenhall, A.Kirk, R.L. Tjoelker, “A Multi-Channel Stability Analyzer for Frequency Standards in the Deep Space Network”, in the proceedings of the 38th Annual Precise Time and Time Interval Meeting (PTTI), Reston, VA; December 2006.
  4. R.L. Tjoelker, M. Calhoun, P.F. Kuhnle, J. Lauf, R.L. Sydnor, “Master Clock and Time Distribution System for the NASA Deep Space Network: Part I”, IPN Progress Report 42-167, November 15, 2006.
  5. S. Huang, R.L. Tjoelker, “All Photonic Link for High Performance Antenna Arraying”, IPN Progress Report 42-167, November 15, 2006.
  6. R. Wang, J. Dick, and R. L. Tjoelker, “Progress Report for a New Cryogenic Sapphire Oscillator”; in the Proceedings of the 2006 IFCS , Miami, FL; June 5-7, 2006.
  7. E. Burt and R.L. Tjoelker, “ Characterization and Reduction of Number Dependent Sensitivity in Multi-pole Linear Ion Trap Standards (LITS)”;in the Proceedings of the 2005 Joint PTTI / IFCS, Vancouver, Canada; Aug 29-31, 2005.
  8. J.D. Prestage, M. Beach, S. Chung, R. Hamell, T. Le, L. Maleki, and R.L. Tjoelker, “One Liter Ion Clock: New Capability for Spaceflight Applications”; Proceedings of the 35 th Annual Precise Time and Time Interval (PTTI) Systems and Applications Meeting , San Diego, CA, Dec. 2003.
  9. R.L. Tjoelker, J.D. Prestage, P.A. Koppang, T.B.Swanson, “ Stability Measurements of a JPL Multi-pole Mercury Trapped Ion Frequency Standard at the USNO” ; Proceedings of the 2003 Joint Meeting of the 17 th EFTF and 58 th Ann. Symp. On Frequency Control , Tampa, FL; May 5-8, 2003.
  10. E. Burt, J.D. Prestage, and R.L. Tjoelker, “Probing Magnetic Field Effects in 12-Pole Linear Ion Trap Frequency Standards” ; Proceedings of the 56th Annual Symp.on Frequency Control, New Orleans, LA; May 27-29, 2002.
  11. J.D. Prestage, E. Burt, S. Chung, L. Maleki, and R.L. Tjoelker, “Stability Measurements Between Two Mercury LITE 12-Pole Clocks”; Proceedings of the 56th Annual Symp.on Frequency Control, New Orleans, LA; May 27-29, 2002.
  12. R.L.Tjoelker, E. Burt, S. Chung, R. Glaser, R. Hamell, L. Lim, L. Maleki, J.D. Prestage, N. Raouf, T. Radey, C. Sepulveda, G. Sprague, B. Tucker, and B. Young, “ Mercury Trapped Ion Frequency Standard For the Global Positioning System”;33 nd Annual Precise Time and Time Interval (PTTI) Systems and Applications Meeting; Long Beach, CA, Nov 27-29, 2001.
  13. John D. Prestage, Robert L. Tjoelker , Lute Maleki, “Recent Developments in Microwave Ion Clocks”, in Topics in Applied Physics 79, Frequency Measurement and Control, A.N. Luiten (Ed.), Springer-Verlag Berlin Heidelberg 2001., pp. 195-211 (2001)
  14. M. Calhoun, R. Wang, A. Kirk, W. Diener, G.J. Dick, and R.L. Tjoelker, “Stabilized Reference Frequency Distribution for Radio Science with the Cassini Spacecraft and the Deep Space Network”, 32 nd Annual Precise Time and Time Interval (PTTI) Systems and Applications Meeting, Reston, VA Nov. 28-30, 2000.
  15. R.L. Tjoelker, W. Diener, A. Kirk, L. Maleki, J.D. Prestage, B. Young, “ Nitrogen Buffer Gas Experiments in Mercury Trapped Ion Frequency Standards” ; Proceedings of the 54th Annual Symp. on Frequency Control, Kansas City, MO; June 7-9, 2000.
  16. R.L. Tjoelker, J.D. Prestage, L. Maleki , “Improved Timekeeping Using Advanced Trapped Ion Clocks”; Proceedings of 31th Ann. Precise Time and Time Interval (PTTI) Planning Meeting ; Dana Point, California; December 5-7, 1999.
  17. J.D. Prestage, R.L. Tjoelker, L. Maleki, “ Higher Pole Linear Traps For Atomic Clock Applications”;13 th European Frequency and Time Forum, Besancon, France, April 13-16, 1999.
  18. G. John Dick, Rabi T. Wang, and Robert L. Tjoelker, “Cryo-cooled Sapphire Oscillator with Ultra-High Stability”, Proceedings of the 52th Annual Symp.on Frequency Control, Pasadena, CA June 1998.
  19. R.L. Tjoelker, J.D. Prestage, L. Maleki , “The JPL Hg+ Extended Linear Ion Trap Frequency Standard: Status, Stability, and Accuracy Prospects”.Proceedings of 28th Ann. Precise Time and Time Interval (PTTI) Planning Meeting , December 3-5, 1996.
  20. R.L. Tjoelker, C. Bricker, W. Diener, R.L. Hamell, A. Kirk, P. Kuhnle, L. Maleki, J.D. Prestage, D. Santiago, D. Seidel, D.A. Stowers, R.L. Sydnor, T. Tucker, “ A Mercury Ion Frequency Standard Engineering Prototype for the NASA Deep Space Network”; Proc. of the 50th Annual Symp.on Frequency Control, Honolulu, Hawaii June 5-7, 1996.
  21. J.D. Prestage, R. L. Tjoelker, and L. Maleki, “ Atomic Clocks and Variations of the Fine Structure Constant”.­Physical Review Letters, 74, 3511, (1995).
  22. R.L. Tjoelker, J.D. Prestage, L. Maleki, “ Record Frequency Stability with Mercury in a Linear Ion Trap”, Proc. of the 1995 Symp. on Frequency Standards and Metrology, Woods Hole, Massachusetts October 11-15, 1995.
  23. R.L. Tjoelker, J.D. Prestage, L. Maleki, “H g+ Linear Trapped Ion Frequen­cy Stan­dard for the USNO”. Proc. of the 49th Annual Symp. on Freq. Control, San Francisco, California, May 31-June 2, 1995.
  24. R.L.Tjoelker, J.D.Prestage, G.J.Dick, L.Maleki; “ Recent Stability Comparisons Between the JPL Hg+ Trapped Ion Frequen­cy Stan­dards”;Proc. of the 48th Annual Symp. on Frequency Control, Boston, MA, June 1-3, 1994.
  25. J.D Prestage, R.L.Tjoelker, G.J. Dick, L. Maleki, “ Hg+ Trapped Ion Frequency Standard with the Superconducting Cavity Maser Oscillator as L.O.”;IEEE Transactions on Instrument and Measurement42, April (1993).
  26. R.L. Tjoelker, G.J. Dick, and L. Maleki, J.D. Prestage, “ Long Term Stability of Hg+ Trapped Ion Frequency Standards”, Proc. of the 47th Annual Symp. on Frequency Control, pp.132-138, (1993).
  27. J.D Prestage, R.L. Tjoelker, G.J. Dick, and L. Maleki, “ Ultra-Stable Hg+ Trapped Ion Frequency Standard”.Journal of Modern Optics39, No. 2, 221-232, (1992).
  28. G.Gabrielse, J. Tan, L.A. Orozco, S.L. Rolston, C.H. Tseng, and R.L. Tjoelker,“ A superconducting solenoid system which cancels fluctua­tions in the ambient magnetic field”.Journal of Magnetic Resonance91, 564-572 (1991).
  29. R. L. Tjoelker , “Antiprotons in a Penning Trap: A New Measurement of the Inertial Mass”; PhD Dissertation, Harvard University, November 1990.
  30. G.Gabrielse, X. Fei, L.A. Orozco, R.L. Tjoelker, T.A. Trainor, J. Haas, H. Kalinowsky, and W. Kells, “ Thousand-fold improvement in the measured antiproton mass”, Physical Review Letters65, 1317 (1990).
  31. G.Gabrielse, X. Fei, L.A. Orozco, R.L. Tjoelker, T.A. Trainor, J. Haas, H. Kalinowsky, and W. Kells, “Cooling and slowing of trapped antiprotons below 100 mev”;Physical Review Letters63, 1360 (1989).
  32. G.Gabrielse, X. Fei, L. Haarsma, S.L. Rolston, R. Tjoelker, T.A. Trainor, H. Kalinowsky, J. Haas, and W. Kells, “ First capture of antiprotons in an ion trap: progress toward a precision mass measurement and antihydrogen”;Physica ScriptaT22, 36 (1988).
  33. G.Gabrielse, X. Fei, K. Helmerson, S.L. Rolston, R. Tjoelker, T.A. Trainor, H. Kalinowsky, J. Haas, and W. Kells, “ First capture of antiprotons in a Penning trap: a kiloelectronvolt source”;Physical Review Letters57, 2504 (1986).
Robert Tjoelker
Address: 
4800 Oak Grove Dr.
Pasadena, CA 91109