ICC24 Program of Papers

SESSION 1: Aerospace Cryocoolers 1
  Tuesday Morning ORAL Session: 8:15 AM to 9:15 AM

Co-Chairs: Jeff Olsen, Lockheed Martin; Ted Conrad, Teledyne FLIR

1.1   Cryocooler System Design and Performance for the Pandora Flight Mission

C.S. Kirkconnell, West Coast Solutions, Huntington Beach, CA; and R.W. Kaszeta, Creare, Hanover, NH; and
J. Karburn, Lawrence Livermore Nat'l Lab, Livermore, CA

1.2   Extended Duration Testing of a 90 K Cryocooler for Space Applications

W.L. Johnson, R.J. Grotenrath, NASA Glenn Research Center, Cleveland OH; M.G. Perkins, HX5, Cleveland OH;
J.R. Stephens, NASA MSFC, Huntsville AL; A. Kashani, ASRC Federal, Moffett Field CA

1.3   HCC Pulse Tube Cryocooler Performance Enhancements

N. Rich, H. Dzigiel, I. Tun, N. Camferdam, Northrop Grumman, Redondo Beach, CA

1.4   Cryocooler/Thermal System Design and Performance on the HyTI-2 Flight Mission

C.S. Kirkconnell, West Coast Solutions, Huntington Beach CA; L. Anderson, Orion Space Systems, Louisville, CO;
M.A. Nunes, Hawaii Space Flight Laboratory, Manoa, HI; I.N. Ruhlich, AIM Infrarot, Heilbronn, Germany; and
R.W. Kaszeta, Creare, Hanover, NH

Plenary 1 (Tuesday Morning, 9:30 AM - 10:30 AM)  

                                Session Chair: Gerd Jakob, ESO

          Cryocooler Applications in Ground-Based Radio Astronomy

P.K. Grimes, Center for Astrophysics, Harvard & Smithsonian, Cambridge, MA

SESSION 2: Cooler Integration Tech. & Applications 1
  Tuesday Morning ORAL Session: 10:30 AM to 11:15 AM

CoChairs: Tim Hanrahan, Bluefors; Mark Zagarola, Creare

2.1   The Performance of a Thales LPT9310 and LPT9310-HP on a Stratospheric Balloon Platform for the
EXCITE Mission

K. Klangboonkrong, A.L. Korotkov, G.S. Tucker, Brown Univ., Providence, RI; and K.R. Helson, P.C. Nagler, and
T.D. Rehm, NASA GSFC, Greenbelt, MD

2.2   Habitable Worlds Observatory Cryocooler Configuration Trade Study

J.R. Olson, M. DeMott, L.D. Schoenrock, A. Carrier, L. Osborne, Lockheed Martin Space, Palo Alto, CA

2.3   Cryocoolers for ESO’s Astronomical Telescopes

G. Jakob, European Southern Observatory, Garching, Germany

SESSION 3: GM & GM-type Pulse Tube Coolers
  Tuesday Morning ORAL Session: 11:15 AM to 12:15 PM

CoChairs: Alan Caughley, Callaghan Innovations; Rich Dausman, Bluefors

3.1   Experimental Apparatus to Study Buffer Tube Performance in Pulse Tube Refrigerators

R. Snodgrass, V. Kotsubo, and J. Ullom, NIST, Boulder, CO and Univ. of Colorado, Boulder, CO

3.2   Analysis of a Pneumatically-Driven Cryocooler Using Acausal Modeling

Q. Bao, Sumitomo Cryogenics of America, Allentown, PA

3.3   Energy Efficiency Improvements on 4.2 K Two-Stage Pulse Tube Cryocoolers

X. Hao, J. Cosco, B. Zerkle and R. Dausman, Bluefors Cryocooler Tech., Syracuse, NY

3.4   Influence of Cycle Frequency on Realized Cooling Power in Gifford-McMahon Cryocoolers

J.W. Reightler, Sumitomo (SHI) Cryogenics of America, Allentown, PA

SESSION 4: Brayton, J-T and Sorption Coolers
  Tuesday Afternoon ORAL Session: 2:00 PM to 3:45 PM

CoChairs: Keisuke Shinozaki, JAXA; Ben Nugent, NASA GRC

4.1   Advanced Helium Compressor for an Ultrahigh-Capacity 20 K Space Cryocooler

D.M. Moore, K.J. Cragin, J.Y. Bieszczad, M.V. Zagarola, Creare, Hanover, NH

4.2   Electrochemical Compressor and Dryer for Hydrogen Joule-Thomson Cryocooler

M. Branco, ESA/ESTEC, Noordwijk, The Netherlands; G. Sdanghi , J. Dillet and G. Maranzana,
Univ. Lorraine, Nancy, France; T. Prouve, CEA/SBT Grenoble, France

4.3   A High-Capacity Two-Stage JT Cryocooler with a Shared Compression Stage

W. Chen, Jet Propulsion Laboratory, Calif. Inst. of Tech., Pasadena, CA

4.4   Application of Space-Borne Turbo-Brayton Cryocooler Technology to Cooling Future Quantum
Computers

M. Zagarola, J. Bieszczad, R. Gilmore, Creare LLC, Hanover, NH

4.5   Cryogenic Performance of the Acoustic Expander

J.L. Adams, C.D. Bunge, R7 Instruments, Somerville, MA

4.6   Emitted Vibration Measurements of Reverse Turbo-Brayton Cryocooler Components

D.M. Moore, K.J. Cragin, M.V. Zagarola, Creare LLC, Hanover, NH; W. Jackson, L. Evans, R. Hon, S. Lust,
C. Kirconnell, West Coast Solutions, Huntington Beach, CA

4.7   Development and Performance of a High-Capacity Closed-Cycle 1 K Cryostat for Low-Temperature Characterization of Superconducting Materials

C. Shao, X. Zhang, Z. Cui and L. Cheng, Shandong Inst. of Adv. Tech., Jinan, China

SESSION 5: Stirling & Pulse Tube Cryocoolers 1
  Tuesday Afternoon ORAL Session: 4:00 PM to 5:30 AM

CoChairs: Franklin Miller, UW-Madison; Ryan Taylor, Ball Aerospace

5.1   Thermal Vacuum Performance and Characterization Testing of the Ricor K508n Cryocoolers

I.M. McKinley, C.D. Hummel, J.I. Rodriguez, Jet Propulsion Laboratory, Calif. Inst. of Tech., Pasadena, CA

5.2   Stationary Testing of a 50 K Pulse Tube Cryocooler Designed to Rotate with the Shaft of a 1.4 MW
Electric Machine

W.R. Sixel, A.D. Anderson, D. Fong, C.J. Theman, J.J. Scheidler, NASA GRC, Cleveland, OH; P. J. Passe, HX5,
Brook Park, OH

5.3   Thales LPT9511 Pulse Tube Cooler for Integrated Detector Dewar Cooler Assembly — Design and
Qualification Status

D. Willems, J. Mullié, G. de Jonge, K. Giesen, C. Vasse, J. Wade, Thales Cryogenics BV, Netherlands

5.4   Environmental Testing of Thales Linear Pulse Tube (LPT) Cryocoolers

I.M. McKinley, C.D. Hummel, B.W. Mueller, J. Keller, L.A. Shaw, R. Sorensen, K. Dang, K. Pham, D.L. Johnson,
J.I. Rodriguez, Jet Propulsion Laboratory, Pasadena, CA

5.5   Stationary testing of a pulse tube cryocooler designed to rotate at 6800 RPM with the superconducting
rotor of an electric machine

W.R. Sixel, A.D. Anderson, D. Fong, C.J. Theman, J.J. Scheidler, NASA Glenn Research Center, Cleveland OH;
P.J. Passe, HX5, Brook Park, OH

5.6   Advances in High Cooling Capacity 4.2 K Two-Stage Pulse Tube Cryocoolers

H. Dang, D. Ma, Y. Zhai, S. Wu, Shanghai Inst. of Tech. Phy., CAS, Shanghai, China; S. Lu, G. Zhou, Shanghai
Boreas Cryogenics Co., Shanghai, China

SESSION 6: Regenerator/Recuperator Investigations
  Wednesday Morning ORAL Session: 8:15 AM to 9:30 AM

CoChairs: Ryan Snodgrass, NIST; Xihuan Hao, Bluefors

6.1   Effectiveness of Cryocoolers Coupled to Graded Heat Exchangers on the System-Level Performance
of Electric Aircraft Cryogenic Power Devices

Y.J. Choi, C.H. Kim, P. Cheetham, and S.V. Pamidi, Florida State Univ., Center for Adv. Power Sys., Tallahassee, FL

6.2   Experimental Investigation on Finned-Tube-in-Tube (FTiT) Recuperators for Joule-Thomson
Cryocoolers

N. Tzabar, T. Halfon, A. Alexeyev, CryoR – Cryogenics Research, Israel

6.3   Development and Testing of a High-Effectiveness Recuperator for Spaceborne Turbo-Brayton
Cryocoolers

A.L. Niblick, R.H. Gilmore, M.V. Zagarola, J.Y. Bieszczad, Creare, Hanover, NH

6.4   Size Effect of Regenerator and Expander Module on the Performance of a Miniature Stirling
Cryocooler

S. K. Garg and M. Singh, SSPL, DRDO, New Delhi, India; B. Premachandran, Mech, Indian Inst. of Tech.,
New Delhi, India

6.5   Flow Resistance Determination in Single and Hybrid Regenerators: A Combined Numerical-Experimental Approach for Resistance Prediction

D. Oztunc, B. Tekin, A. Aksin, and A.B. Erdogmus, Aselsan, Ankara, Turkey

Special Session: Ray Radebaugh Memorial

          Wednesday Morning, 9:45 - 10:45 AM

In Memoriam: Dr. Ray Radebaugh 

                            Chair: Peter Bradley, NIST

SESSION 7: Aerospace Cryocoolers 2
  Wednesday Morning ORAL Session: 10:45 AM to 11:45 AM

CoChairs: Carl Kirkconnel, WECOSO; Ali Kashani, NASA ARC

7.1   JT Cooler Technology Development for Ariel

M. Crook, M. Hills, G. Gilley, C. Padley, S. Brown, B. Green, A. Orme, R. Crook, L. Gibbs, R. Carver, B. Gillot,
S. McCluskey, STFC Rutherford Appleton Laboratory, Oxford, UK

7.2   Characterization Testing of a 20 Kelvin Cryocooler for Space Applications

B.T. Nugent, R.J. Grotenrath, W.L. Johnson, NASA GRC, Cleveland, OH; J.R. Stephens, NASA MSFC, Huntsville, AL;
M.G. Perkins, HX5, Brook Park, OH

7.3   Ariel Active Cooler System: Progress Towards the QM

M. Crook, M. Hills, G. Gilley, C. Padley, S. Brown, B. Green, A. Orme, R. Crook, L. Gibbs, R. Carver, B. Gillot,
S. McCluskey, STFC Rutherford Appleton Laboratory, Oxford, UK

7.4   Launch Vibration Qualification Testing of a High-Capacity 20K Cryocooler for Cryo Fluid
Management

K.J. Cragin and M.V. Zagarola, Creare, Hanover, NH

SESSION 8: Cooler Integration & Applications
  Wednesday Afternoon POSTER Session: 1:45 PM to 3:15 PM

CoChairs: Santhosh Gandla, SHI Cryogenics; Tim Hanrahan, Bluefors

8.1   Performance Modeling of CryoFILL Incorporating a Flight-Like Cryocooler

R.J. Grotenrath, D.M. Hauser, M.G. Perkins, W.L. Johnson, NASA GRC, Cleveland, OH; R. Balasubramaniam,
Case Western Reserve Univ., Cleveland, OH

8.2   Modelling and Experimentation of Cryostat Heating During Alternating Current (AC) in a
Superconducting Coil

J. Nalbach, P. Ferrara, M. Sylvia, A. Bruno, Naval Surface Warfare Cntr, Philadelphia, PA

8.3   Summery Review of System Thermal Performance for the wSMA Cryostat as Built by
FormFactor

P. Owen, M. Deming, J. West, FormFactor, Boulder, CO

SESSION 9: Cryocooler Characterization
  Wednesday Afternoon POSTER Session: 1:45 PM to 3:15 PM

CoChairs: Santhosh Gandla, SHI Cryogenics; Tim Hanrahan, Bluefors

9.1   Characterization Testing of the Thales LSF9589 Cryocooler

B.D. Moore, I.M. McKinley, Jet Propulsion Laboratory, Calif. Inst. of Tech., Pasadena, CA

9.2   Thermal Vacuum Performance and Characterization Testing of the Sunpower GT and GTLT
Cryocoolers

I.M. McKinley, C.D. Hummel, J.I. Rodriguez, Jet Propulsion Laboratory, Calif. Inst. of Tech., Pasadena, CA

9.3   Characterization Testing of Joule-Thomson Coolers for Space Science Missions

K. Shinozaki, H.Tanaka, K.Tanaka, H. Sugita, JAXA/R&D; Y. Sato, JAXA/ETTU; S. Tsunematsu and K. Kanao,
SHI, Japan

SESSION 10: Stirling Cryocoolers
  Wednesday Afternoon POSTER Session: 1:45 PM to 3:15 PM

CoChairs: Qian Bao, SHI Cryogenics; Hannah Rana, Harvard Smithsonian

10.1   Development and Performance Test of a High-Capacity Two-Stage Stirling Cryocooler

X. Wang, Y. Cui, and W. Dai, St Key Lab of CS&T, Tech. Inst. of Phy. and Chem., CAS, Beijing, China; S. Huang,
S. Chen, Y. Zhang H. Li, Lihan Cryogenics Co., China

10.2   Interpretable Machine Learning Models for Cryocooler Performance Mapping and Fatigue Life

H. Rana, Center for Astrophysics, Harvard & Smithsonian, Cambridge, MA

10.3   A Novel 3D Printed Regenerator Filler for Large Stirling and Pulse-Tube Cryocoolers

A. Ghavami, West Coast Solution and Georgia Tech; C. Kirkconnell and R. Hon, West Coast Solutions,
Huntington Beach, CA; S.M. Ghiaasiaan, Georgia Tech, Atlanta, GA

SESSION 11: GM and JT Cryocoolers
   Wednesday Afternoon POSTER Session: 1:45 PM to 3:15 PM

CoChairs: Qian Bao, SHI Cryogenics; Hannah Rana, Harvard Smithsonian

11.1   Experimental Study of a Large-Capacity GM–JT Cryocooler in the Liquid Helium Temperature Range

Y. Cui, X. Wang, Z. Li, Y. Wang, W. Dai and E. Luo, St Key Lab of CS&T, Tech. Inst. of Phy. and Chem., CAS,
Beijing, China

11.2   Experimental Investigation of a Quartz Tuning Fork as a Flow-Phase Monitoring Sensor for a
Joule–Thomson Cryocooler

T. Shimazaki and H. Nakagawa, Nat'l l Metrology Inst. of Japan, Nat'l Inst. of Adv. Ind. Sci. and Tech.,
Tsukuba, Japan

11.3   High-Efficiency Operation of Multiple Single-Stage GM Cold Heads Powered by a Single
Compressor

S. Masuyama, NIT, Oshima College, Yamaguchi, Japan; K. Natsume, K. Kamiya and T. Numazawa, NIMS,
Ibaraki, Japan

SESSION 12: Stirling & Pulse Tube Cryocoolers 2
  Wednesday Afternoon ORAL Session: 3:15 PM to 4:45 PM

CoChairs: Brad Moore, NASA JPL; Nick Rich, NGC

12.1   Thermal-Vacuum Performance and Characterization Testing of the Thales R3Mi Cryocoolers

I.M. McKinley, C.D. Hummel, J.I. Rodriguez, Jet Propulsion Laboratory, Calif. Inst. of Tech., Pasadena, CA

12.2   Cost-Effective and Compact Linear Piston Compressor for Low SWaP IR Applications

A.Veprik, CTO, Israel

12.3   High Efficiency, "Zero" Ripple Cooler Electronics for Small Satellite Space Sensors

C.S. Kirkconnell, J.B. Murphy, Z. Chow, and N.A. Hudson, West Coast Solutions, Huntington Beach, CA USA;
and A.M. Veprik, Ricor, En Harod Ihud, Israel

12.4   Performance Characterization and Micro-Vibration Mitigation of the Air Liquide LPTC Driven by
Creare’s Miniature Cryocooler Control Electronics (MCCE)

Y. Juanico, P.-O. Mine, K. Benadibah, and A. Bakkas, Air Liquid Adv. Tech., Sassenage, France; R.W. Kaszeta,
M.V. Zagarola, J. Greenhalgh, and J. Gregoire, Creare, Hanover, NH; J.Baxter, N. Hudson, W. Jackson, and
C. Kirkconnell, West Coast Solutions, Huntington Beach, CA

12.5   Machine-Learning-Based Approaches for Advanced Cryocooler Design

H. Tanaka, K. Shinozaki, JAXA / R&D, Sagamihara, Japan; K. Tanaka, JAXA / R&D, Tsukuba, Japan; Y. Sato,
JAXA / ETTU, Tsukuba, Japan

12.6   Research on the Influence of Operating Conditions on the Cool-down Time of Miniature
Pulse Tube Cryocoolers

Z. Yang, L. Xu, Z. Luo, X. Zhi, L. Qiu, Zhejiang Univ., Hangzhou, China

SESSION 13: Cooler Integration Tech. & Applications 2
  Thursday Morning ORAL Session: 8:15 AM to 9:45 AM

CoChairs: Wes Johnson, NASA GRC; Sastry Pamidi; Florida State

13.1   A Container-Based 100 kg/day Hydrogen Reliquefier

A.J. Caughley, Univ. of Canterbury, Christchurch, New Zealand; N. Glasson, J. Meier, J. Clauss, H. Reynolds,
Fabrum, Christchurch, New Zealand.

13.2   Development of a Low Power Helium Reliquefier for NMR Users

G. Harrington, X. Hao, and B. Zerkle; Bluefors Cryocooler Technologies Inc., Syracuse, NY

13.3   Performance of a Pulse Tube + 4He Custom JT in a Laboratory Cryostat for Ground Tests of Space
Applications

L. Marelli, A. Simone, and J. André, CNES, Toulouse, France; P. Camus, S. Dang and T. Trollier, Absolut System,
Eybens, France

13.4   Progress on Design of Cryostat for a Cryocooler-Cooled Superconducting ECR Ion Source MARS-D
Magnet at LBL

L. Wang, J.Y. Benitez, D. Todd, L. Xu, Y. Yang, Lawrence Berkeley Nat'l Lab, Berkeley, CA

13.5   Realization of Cryogenic Fixed Points for Calibration of Capsule-Type SPRTs Using GM
Cryocooler

I. Yang, Korea Research Inst. of Standards and Science, Daejeon, South Korea

13.6   Performance and Operational Characteristics of FormFactor’s GM-Driven Horizontal Tabletop Dilution Refrigerator

L. Kossel, P. Owen, K. Montoya, B. Toback, K. Faulkner, M. Snow, J. West, FormFactor, Boulder, CO

Plenary 2 (Thursday Morning, 10:00 - 11:00 AM)  

              Session Chair: Andrew Ballard, Bluefors

          Quantum Emulation with Superconducting Quantum Processors

M. Hays, C. N. Barrett ,G. Kim, S. Muschinske, H. Zhang, J. An, J. A. Grover, W. D. Oliver, MIT, Cambridge, MA; R. Das,
D. K. Kim, B. M. Niedzielski, M. Schuldt, J. L. Yoder, K. Serniak, M. E. Schwartz, MIT Lincoln Laboratory, Lexington, MA

SESSION 14: Cryogenic Technology
  Thursday Morning ORAL Session: 11:00 AM to 12:15 PM

CoChairs: Peter Bradley, NIST; Moritz Branco, ESA

14.1   Estimation of Thermal Conduction Loads of Cryogenic Components in Spaceflight Applications

I.M. McKinley, W. Chen, B.D. Moore, J.I. Rodriguez, R.G. Ross Jr., Jet Propulsion Laboratory, Calif. Inst. of Tech.,
Pasadena, CA

14.2   Sub-Kelvin Cryogenics for a Super-Pressure Balloon-Borne CMB Polarimeter: Taurus

J. May, et al., Case Western Reserve Univ., Cleveland, OH

14.3   Sub-Triple-Point Nitrogen Spray Cooling

C.B. Kreft, F.K. Miller, Univ. of Wisconsin-Madison, Madison, WI

14.4   Quantitative Measure of Cryocooler Contamination Using Cold-Trap Fractionation

D. Wilcox, W. Logan, MVE Biological Solutions, Ball Ground, GA; Phil Spoor, Phuzzy Arts & Science, Waterford, NY

14.5   Crazy Pulse Tube Cryocooler Ideas

J.R. Olson, Lockheed Martin Space, Palo Alto, CA

SESSION 15: Sub Kelvin Refrigerators & Technology
  Thursday Afternoon ORAL Session: 1:45 PM to 3:00 PM

CoChairs: Mike Dipirro, NASA GSFC; Jean-Marc Duval, CEA

15.1   Progress on Vanadium Superconducting Heat Switch Development at UW-Madison

A.M. Feucht, S.E. Therien, E.M. Cueva, S.F. Dougherty, O. Dobson, G.F. Nellis, F.K. Miller, Univ. of Wisconsin-Madison, Madison, WI; W.A. Holmes, Jet Propulsion Laboratory, Pasadena, CA

15.2   Research on Matching Optimization of Salt Pills in a Two-Stage Series Continuous Adiabatic
Demagnetization Refrigerator

Y. Cao, Y.N. Zhao, L. Yang, Beijing Inst. of Tech., Beijing, China; Y.A. Lu, J. Shen, Tech. Inst. of Phy. and Chem.,
CAS, Univ. of CAS, Beijing, China

15.3   Mitigation of Continuous Adsorption Cooler Periodic Fluctuations in Dilution Unit Precooling

Y.A. Lu, J. Shen, Tech. Inst. of Phys. and Chem., CAS, Beijing, China; Y.N. Zhao, Y. Cao, L. Yang, Dept. of Energy
and Power Engin., Beijing Inst. of Tech., Beijing, China

15.4   Optimization of the Transient Response of Gas-Gap Heat Switches

Y.X. Wang, T. Pan, Y.N. Li, K. Li, and W. Dai, St Key Lab of CS&T, Tech. Inst. of Phy. and Chem., CAS, and Univ. of
CAS, Beijing, China

15.5   Experimental Study of a Superfluid Heat Pump-Driven Dilution Refrigerator Pre-Cooled by a Two-Stage Adsorption Cooler

Z. Li, W. Cheng, Y. Ran, St Key Lab of CS&T, Tech. Inst. of Phy. and Chem., CAS, Univ. of CAS, Beijing, China; and
Y. Wang, W. Dai, St Key Lab of CS&T, Tech. Inst. of Phy. and Chem, CAS, Beijing, China.

SESSION 16: Aerospace Cryocoolers Athena & Prima Missions
  Thursday Afternoon ORAL Session: 3:00 PM to 4:30 PM

CoChairs: Kim Banks, NASA GSFC; Weibo Chen, NASA JPL

16.1   Advances in the Continuous Adiabatic Demagnetization Refrigerator Suspension System

M. DiPirro, R. Ottens, M. Kimball, J. Titus, E. Canavan, P. Shirron, and S. Hagopian, NASA/Goddard Space
Flight Center, Greenbelt, Maryland

16.2   50 mK ADR Cooler for the Athena Space Mission: 5-Stages Functional Results

J.M. Duval, A. Attard, F. Bancel, I. Charles, J.L. Durand, S. Martin, Univ. Grenoble Alpes, CEA, IRIG, DSBT, Grenoble, France; C. Marin, Univ. Grenoble Alpes, CEA, IRIG, PHELIQS, Grenoble, France; E. Bellouard, CNES, Toulouse, France

16.3   Four-Stage Pulse Tube Cryocooler for NewAthena

J.R. Olson, H. Yengoyan, S. Ham, M. DeMott, V. Macasaet, E. Roth, B. Evtimov, L. Osborne, Lockheed Martin Space,
Palo Alto, CA

16.4   Northrop Grumman NewAthena DM Cryocooler Test Results

H. Dzigiel, G. Abraham, N. Camferdam, Northrop Grumman, Redondo Beach, CA

16.5   BAE Hybrid Cryocooler Solution for the ESA Athena Mission

Y. Kim, K.Westhoff, R.Taylor, C. Mock, B. Buchholtz, B. Drillick, and D.Glaister, BAE Systems, Space and Mission Sys., Boulder, CO

16.6   On-Orbit Thermal Performance and Correlation of the SPHEREx Passive Cryogenic System

B.D. Moore, D.A. Bolton, Jet Propulsion Laboratory, Calif. Inst. of Tech., Pasadena, CA; P.M. Korngut, J.J. Bock, Calif.
Inst. of Tech., Pasadena, CA; F.K. Miller, Univ. of Wisconsin - Madison, WI