Mr. Nachman Pundak Profile

Nachman Pundak

General Manager at RICOR-Cryogenic & Vacuum Systems

SPIE Involvement:

Author

Publications (26)

Proceedings Article | 5 May 2017 Presentation + Paper

Ricor's anniversary of 50 innovative years in cryogenic technology

Avishai Filis, Victor Segal, Nachman Pundak, Zvi Bar Haim, Menachem Danziger

Proceedings Volume 10180, 101800E (2017) https://doi.org/10.1117/12.2261923

KEYWORDS: Liquids, Medical research, Therapeutics, Patents, Magnetism, Safety, Infrared detectors, Reliability, Nitrogen, Infrared imaging

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Proceedings Article | 21 May 2011 Paper

RICOR's new development of a highly reliable integral rotary cooler: engineering and reliability aspects

Avishai Filis, Nachman Pundak, Moshe Barak, Ze'ev Porat, Mordechai Jaeger

Proceedings Volume 8012, 80122O (2011) https://doi.org/10.1117/12.884218

KEYWORDS: Reliability, Cryocoolers, Accelerated life testing, Mechanical engineering, Data modeling, Electro optical modeling, Standards development, Systems modeling, Interfaces, Clocks

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Proceedings Article | 21 May 2011 Paper

Adaptation of the low-cost and low-power tactical split Stirling cryogenic cooler for aerospace applications

A. Veprik, S. Zechtzer, N. Pundak, C. Kirkconnell, J. Freeman, S. Riabzev

Proceedings Volume 8012, 80122I (2011) https://doi.org/10.1117/12.883650

KEYWORDS: Cryogenics, Cryocoolers, Electronics, Space operations, Reliability, Digital signal processing, Sensors, Actuators, Aerospace engineering, Satellites

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Proceedings Article | 21 May 2011 Paper

Low vibration microminiature split Stirling cryogenic cooler for infrared aerospace applications

A. Veprik, S. Zechtzer, N. Pundak, C. Kirkconnel, J. Freeman, S. Riabzev

Proceedings Volume 8012, 80122J (2011) https://doi.org/10.1117/12.886360

KEYWORDS: Cryogenics, Vibration isolation, Aerospace engineering, Infrared radiation, Reliability, Digital signal processing, Actuators, Space operations, Sensors, Electronics

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Proceedings Article | 4 May 2010 Paper

Split Stirling linear cryogenic cooler for a new generation of high temperature infrared imagers

A. Veprik, S. Zechtzer, N. Pundak

Proceedings Volume 7660, 76602K (2010) https://doi.org/10.1117/12.851004

KEYWORDS: Cryogenics, Imaging systems, Infrared imaging, Infrared radiation, Cryocoolers, Actuators, Image compression, Infrared detectors, Head, Staring arrays

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Proceedings Article | 4 May 2010 Paper

Cryocoolers for infrared missile warning systems

Avishai Filis, Nachman Pundak, Yoav Zur, Ramon Broyde, Moshe Barak

Proceedings Volume 7660, 76602L (2010) https://doi.org/10.1117/12.850006

KEYWORDS: Cryocoolers, Medium wave, Missiles, Staring arrays, Infrared imaging, Infrared radiation, Optimization (mathematics), Analog electronics, Reliability

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Proceedings Article | 7 May 2009 Paper

Split Stirling linear cryogenic cooler for high-temperature infrared sensors

A. Veprik, S. Zehter, H. Vilenchik, N. Pundak

Proceedings Volume 7298, 729816 (2009) https://doi.org/10.1117/12.819219

KEYWORDS: Cryogenics, Infrared imaging, Thermography, Infrared radiation, Electronics, Infrared sensors, Imaging systems, Staring arrays, Cryocoolers, Head

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Proceedings Article | 7 May 2009 Paper

Novel concept for driving the linear compressor of a micro-miniature split Stirling cryogenic cooler

V. Maron, A. Veprik, L. Finkelstein, H. Vilenchik, I. Ziv, N. Pundak

Proceedings Volume 7298, 72981A (2009) https://doi.org/10.1117/12.819220

KEYWORDS: Cryogenics, Power supplies, Infrared imaging, Infrared radiation, Control systems, Bridges, Infrared technology, Homeland security, Imaging systems, Staring arrays

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New methods of carrying out homeland security and antiterrorist operations call for the development of a new generation of mechanically cooled, portable, battery powered infrared imagers, relying on micro-miniature Stirling cryogenic coolers of rotary or linear types. Since split Stirling linearly driven micro-miniature cryogenic coolers have inherently longer life spans, low vibration export and better aural stealth as compared to their rotary driven rivals, they are more suitable for the above applications. The performance of such cryogenic coolers depends strongly on the efficacy of their electronic drivers. In a traditional approach, the PWM power electronics produce the fixed frequency tonal driving voltage/current, the magnitude of which is modulated via a PID control law so as to maintain the desired focal plane array temperature. The disadvantage of such drivers is that they draw high ripple current from the system's power bus. This results in the need for an oversized DC power supply (battery packs) and power electronic components, low efficiency due to excessive conductive losses and high residual electromagnetic interference which in turn degrades the performance of other systems connected to the same power bus. Without either an active line filter or large and heavy passive filtering, other electronics can not be powered from the same power bus, unless they incorporate heavy filtering at their inputs. The authors present the results of a feasibility study towards developing a novel "pumping" driver consuming essentially constant instant battery power/current without making use of an active or passive filter. In the tested setup, the driver relies on a bidirectional controllable bridge, invertible with the driving frequency, and a fast regulated DC/DC converter which maintains a constant level of current consumed from the DC power supply and thus operates in input current control mode. From the experimental results, the steady-state power consumed by the linear compressor remains the same as compared with the traditional sine wave driver, the voltage and current drawn from the battery pack is essentially free of low frequency ripple (this without use of any kind of filtering) and the overall coefficient of performance of the driver is in excess of 94% over the entire working range of supply voltages. Such a driver free of sine forming PWM stage and have reduced power peaks in all power conversion components.

Proceedings Article | 7 May 2009 Paper

Microminiature rotary Stirling cryocooler for compact, lightweight, and low-power thermal imaging systems

Avishai Filis, Zvi Bar Haim, Nachman Pundak, Ramon Broyde

Proceedings Volume 7298, 729818 (2009) https://doi.org/10.1117/12.818427

KEYWORDS: Sensors, Staring arrays, Thermography, Infrared detectors, Cryocoolers, Infrared radiation, Reliability, Infrared imaging, Infrared sensors, Thermodynamics

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Novel compact and low power consuming cooled infrared thermal imagers as used in gyro-stabilized payloads of miniature unmanned aerial vehicles, Thermal small arms sights and tactical night vision goggles often rely on integral rotary micro-miniature closed cycle Stirling cryogenic engines. Development of EPI Antimonides technology and optimization of MCT technology allowed decreasing in order of magnitudes the level of dark current in infrared detectors thus enabling an increase in the optimal focal plane temperature in excess of 95K while keeping the same radiometric performances as achieved at 77K using regular technologies. Maintaining focal plane temperature in the range of 95K to 110K instead of 77K improves the efficiency of Stirling thermodynamic cycle thus enlarging cooling power and enabling the development of a mini micro cooler similar to RICOR's K562S model which is three times smaller, lighter and more compact than a standard tactical cryocooler like RICOR's K508 model. This cooler also features a new type of ball bearings and internal components which were optimized to fit tight bulk constraints and maintain the required life span, while keeping a low level of vibration and noise signature. Further, the functions of management the brushless DC motor and temperature stabilization are delivered by the newly developed high performance sensorless digital controller. By reducing Dewar Detector thermal losses and increasing the focal plane temperature, longer life time operation is expected as was proved with RICOR's K508 model. Resulting from this development, the RICOR K562S model cryogenic engine consumes 1.2 - 3.0 WDC while operating in the closed loop mode and maintaining the typical focal plane arrays at 200-100K. This makes it compatible with very compact battery packages allowing further reduction of the overall thermal imager weight thus making it comparable with the compatible uncooled infrared thermal imager relying on a microbolometer detector in terms of power consumption and bulk.

Proceedings Article | 7 May 2009 Paper

Field reliability of Ricor microcoolers

N. Pundak, Z. Porat, M. Barak, Y. Zur, G. Pasternak

Proceedings Volume 7298, 72983I (2009) https://doi.org/10.1117/12.816262

KEYWORDS: Reliability, Failure analysis, Cryocoolers, Statistical analysis, Systems modeling, Fused deposition modeling, Cryogenics, Statistical modeling, Infrared technology, Current controlled current source

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Proceedings Article | 17 April 2008 Paper

Ultra-low vibration linear stirling cryogenic refrigerator for sub-nano resolution microscopy

S. Riabzev, A. Veprik, H. Vilenchik, N. Pundak, E. Castiel

Proceedings Volume 6940, 69402C (2008) https://doi.org/10.1117/12.792191

KEYWORDS: Cryogenics, Head, Field programmable gate arrays, Prototyping, Image resolution, LabVIEW, Active vibration control, Microscopy, Vibration control, Microscopes

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