Development of a quadrupolar trap for investigating ice formation and cloud electrification

[This topic is open to only those students who have been selected under the Joint Masters Program between IITB - Washington University in St. Louis] The topic will be jointly supervised by Prof. Thaokar and Prof. Jian from WUStL.

Clouds can both shade the Earth and trap heat, therefore strongly influencing the global climate. Which of the two effects dominates depending on how reflective the clouds are, the altitudes of clouds, and whether it is day or night. Clouds may produce precipitation, which is the primary route for water to return to the Earth's surface within the water cycle. Clouds have long been the largest uncertainty in climate calculations. The properties of clouds and formation of precipitation are driven by a variety of processes that remain poorly understood, including formation, growth, and evaporation of ice particles, secondary ice formation, and cloud electrification. Electrodynamic trapping is a versatile technique that can be used to suspend cloud droplets and ice particles of various sizes in chambers under a wide range of representative conditions, making it an ideal tool for investigating some of the key cloud processes.

Conducting systematic studies on suspended cloud droplets such as ice particles is rendered difficult due to imminent action of gravity that would tend to settle the particles. The gravity defying act of levitating liquid droplets and solid particles in air has important technological applications. In recent work in Prof Thaokar’s lab a quadrupolar trap was fabricated that can levitate charged droplets. It should be noted that Prof Wolfgang Paul got Nobel Prize for this discovery. The quadrupole trap for charged liquid drop shows Rayleigh breakup and is used for Ion mass spectrometry. Prof John Fenn got a Nobel prize for development of Ion mass spectrometry. Studies on  Rayleigh breakup were also conducted recently in Prof Thaokar’s lab.

The project aims at development of a quadrupolar trap to levitate ice particles to systematically study formation, growth, and evaporation of ice particles, secondary ice formation, and cloud electrification. The  SLP project will involve a thorough literature search and derivation of relevant equations for this objective. The project will be under the Washington University/IIT Bombay joint DD program category. While Professor Jian from Washington University is expert in aerosols and cloud physics, Professor Thaokar at IIT Bombay looks at charged droplets, their levitation and breakup. Two representative publications are given below.


  1. JH Slade, M Shiraiwa, A Arangio, H Su, U Pöschl, J Wang, DA Knopf Geophysical Research Letters 44 (3), 1583-1591
  2. Levitation dynamics of a collection of charged droplets in an electrodynamic balance M Singh, YS Mayya, J Gaware, RM Thaokar Journal of Applied Physics 121 (5), 054503
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