Plenary Speakers

Molecular Movies with an X-Ray Laser

Professor John Spence
Physics Department, Arizona State University, Tempe, Az. USA

The aim of making movies of molecular machines at work, for processes as fundamental as photosynthesis (which makes life possible on earth) to drug action, was greatly advanced by the recent invention of the X-ray laser (XFEL). The fascinating history of this, going back to travelling-wave amplifier vacuum tubes and klystrons, will be briefly reviewed along with an outline of how XFELs work. Their ability to out-run radiation damage by the “diffract-and-destroy” method, using femtosecond pulses which end before damage starts, opens completely new vistas for imaging room-temperature molecular dynamics at atom resolution and sub-picosecond speeds (1). Prof. Spence will compare high-energy electron beams with X-rays for this purpose, and discuss damage mechanisms and time-scales. He will review his work using the hard X-ray pulsed laser at SLAC (the LCLS) within the 6-campus NSF consortium “BioXFEL” (http://www.bioxfel.org), which applies X-ray lasers (XFELs) to Structural Biology. He’ll show molecular movies from light-sensitive proteins with 150 fs time resolution and near-atomic spatial, using both crystals and solution scattering obtained from the LCLS XFEL at SLAC, and very recent single-particle virus images (one virus per shot) showing dynamics. Dr. Spence will discuss work in his lab on methods for hydrated sample delivery for an XFEL, and the compact inverse Compton XFEL under construction on the ASU campus, which uses a laser as an undulator. Finally, he will review a recent proposal for the use of intensity interferometry to analyze the angular dependence of inner-shell X-ray fluorescence from a molecule. 

1. J.Spence. XFELS for structure and dynamics in biology. IUCrJ 4, 322 (2017). 

Regents’ Prof John C.H. Spence FRS is Richard Snell Professor of Physics at Arizona State University where he teaches condensed matter physics. He completed a Ph.D. in physics at Melbourne University in Australia, followed by postdoc at Oxford University’s materials department. His group undertakes research in diffraction physics and new microscopies for materials science and biology. See https://live- spence.ws.asu.edu. He is a Foreign Member of the Royal Society, the author of texts on electron microscopy, and was awarded the Buerger Medal of ACA, the Cowley Medal of IFSM and the Distinguished Scientist Medal of MSA. He is currently director of science for the NSF’s BioXFEL Science and Technology Center, devoted to the application of X-ray lasers for imaging structure and dynamics in molecular biology. 

 

The Emergence of HTS Systems and What It Means to the Future of Space TWTAs

Hampton Chan
Vice President Payload Systems
SSL , A Business Unit of Maxar Technologies

Mr. Chan will discuss his views, from the perspective of a satellite systems architect, on the emergence of High Throughput Satellite (HTS) systems, current HTS architecture, and what it means to vacuum electronics, particularly space Traveling Wave Tube Amplifiers. This includes a brief discussion on the comparison between GSO HTS and Non-GSO HTS constellation systems and whether GaN Solid State Power Amplifier technology is a threat to the future of space TWTAs.

Mr. Chan is Vice President of Payload Systems at SSL, a business unit of Maxar Technologies. He has been in the satellite industry for 30 years with the last 22 years at SSL. In his current role, he is responsible for SSL’s payload systems from business development support and program award to final system delivery. His organization consists of communications systems engineering, communications mission engineering, antenna and tower engineering, communications panel engineering, and RF subcontract engineering. Mr. Chan has held several key management positions at SSL, including Chief Architect, Executive Director of Advanced Programs and Systems, and Executive Director of Payload Systems Engineering.

Prior to joining SSL in 1995, Mr. Chan was with Hughes Space and Communications Group.

Mr. Chan holds a master’s degree in electrical engineering from Stanford University and a bachelor’s degree in electrical engineering from the University of Hawaii at Manoa.

 


Testing the limits of Materials and Plasmas at the FACET Facility at SLAC 

Dr. Vitaly Yakimenko
SLAC National Accelerator Laboratory

The FACET facility at SLAC National Accelerator Laboratory has recently concluded a five-year campaign to study the interaction of high energy electron and positron beams with matter and lasers. Experiments studying plasma wakefield acceleration have operated with 10’s GV/m accelerating fields orders of magnitude greater than possible than in structures made out of metals. Experiments involving Dielectric Wakefield Accelerators (DWA) produce GeV/m gradients in SiO2 structures operating in the THz frequency range and effects such as high-field induced dielectric metallization have been observed. The same extreme beams that produce large wakefields in plasma and dielectric structures have been used to test the limits of metallic structures, have probed the ability of crystals to channel particles and tested the speed limit for switching magnetic states. FACET-II is a new test facility at SLAC designed to generate beams with up to 300 kA peak current and shorter than 1 μm bunch lengths at 10 GeV. FACET-II will operate as a National User Facility delivering beams to a broad array of experiments studying concepts for advanced accelerators and radiation sources. 

Vitaly earned B.Sc. in Physics and Mathematics, from the Novosibirsk State University, Ph.D. in Accelerator Physics, from the Budker Institute for Nuclear Physics. Vitaly Yakimenko joint Brookhaven National Laboratory in 1996 as a Post Doc became ATF User Facility Director in 2006. He joint SLAC as FACET National User Director in 2012 and currently leading FACET-II project. Vitaly is a Fellow of American Physics Society and a recipient of the IEEE Particle Accelerator Science and Technology Award. He served in various committees and review panels. He is the author or co-author of over many publications in referred journals and conference proceedings. 

 

The Development of Vacuum Electronics in China 

Prof. Yubin Gong
National Key Lab of science and Technology on Vacuum Electronics, University of Electronic Science and Technology of China, Chengdu, 610054, China 

Prof. Jinjun Feng
National Key Lab of science and Technology on Vacuum Electronics, Beijing Vacuum Electronics Research Institute, Beijing, 100015, China 

From the birth of the vacuum diode, vacuum electronics has a history of more than 100 years. Like all other countries in the world, vacuum electronics in China is also facing serious challenges from the third generation semiconductor devices. In response to this challenge, China has some explorations to maintain the sustainability of microwave vacuum devices in such areas as under and post graduate education system, attraction of young scientists into the field of vacuum electronics and basic research. 

The universities and the institutes currently engaged in vacuum electronics education and research in China include University of Electronic Science and Technology of China (UESTC), Southeast University (SEU), Beijing Vacuum Electronics Research Institute (BVERI), Institute of Electronics of Chinese Academy of Sciences(IECAS), and so on. In addition, as a bridge between universities and research institutes, the joint National Key Lab of Science and Technology on vacuum electronics based on BVERI and UESTC plays an important role. 

Main types of vacuum electron devices are studied, developed and produced in China, such as traveling wave tubes, klystrons, magnetrons, gyrotrons, backward wave oscillators, etc. In the area of basic research and advanced technology, the main work focuses on modeling and simulation, novel slow wave structures, miniaturization, integration, modularization, micro-fabrication, metamaterials, field emission cathodes and nano-material thermionic cathodes. At the same time, research work on high frequency devices is also carried out. 

This lecture will mainly introduce the development of vacuum electronics in China covering the education system, basic research, and frontier technology in recent years. 

Prof. Yubin Gong was born in 1967. He got his bachelor degree in the major of applied optics from Changchun University of Science and Technology in 1989,master and Ph.D. degree of physical electronics from University of Electronic Science and Technology of China (UESTC) in 1991 and 1998, respectively. 

He joined UESTC as a research assistant in 1992, and was promoted as a full professor in 2001. And now he is the Yangzi scholarship distinguished professor in the major of physical electronics in UESTC. He is also the deputy director of the National Key Lab of Science and Technology on Vacuum Electronics.

He has been engaged in academic research and teaching in the field of vacuum electronics for 27 years. He gives lectures to under- and post-graduate students on five subjects of microwave electronics, electromagnetic field and waves, relativistic electrodynamics, principle and application of the accelerators, principle and application of electromagnetic radiation of the charged particles. He has authored and co-authored over 200 papers in journals and conferences in the field of microwave, millimeter and THz vacuum devices including design, simulation and experiment of slow wave structures, electron optics system etc.