Charles K. (Ned) Birdsall’s discoveries have built the foundations of plasma science. His lifelong dedication to plasma physics began during the 1950s with work on resistive-wall amplification. He showed that electron streams could be amplified by the presence of a resistive wall and proved the existence of negative energy waves. He pioneered the concept of coupling between positive and negative energy waves. Dr. Birdsall’s ring-bar travelling wave tube (TWT), a high-power amplifying device, is still in use today for broadband military communications. During the 1960s he discovered virtual cathode oscillations, the most important theoretical development in diode physics. He is best known for establishing particle-in-cell simulation, which provides first principle solutions of a wide range of plasma phenomena. Dr. Birdsall’s free dissemination of plasma simulation codes has facilitated thousands of engineers in conducting research. An IEEE Life Fellow, Dr. Birdsall is Professor Emeritus in the Electrical Engineering and Computer Science Department at the University of California, Berkeley.