C16. Commission on Plasma Physics

Report to the 2005 General Assembly for the period 2002-2005
Cape town, S. Africa
October 26-28, 2005

The General Aims of the Commission on Plasma Physics (C16) are:

To promote the exchange of information and views among the members of the international scientific community in the general field of Plasma Physics including:

1. the physics of ionized gases, of partially ionized gases, and of gaseous electronics
2. the applications of such physics including thermonuclear fusion, space physics, astrophysics, and plasma technology.

To recommend for Union sponsorship international conferences which qualify for support under Union regulations.

To promote the free circulation of scientists; to assist conference organizers in ensuring such free circulation and in resolving potential infringements.

1. Activities

The Commission had three formal meetings each on the occasion of one of the two major conferences sponsored by C16. These were the 16th and 17 th International Conference on Phenomena in Ionized Gases (ICPIG) held at Greiswald, Germany,( July 15-20, 2003),

and at Eindhoven, Netherlands (July 17-22 2005), and the 12 th International Congress on Plasma Physics held at Nice, France (October 25-29, 2004). In addition the members conducted their business through an active exchange of emails.

Following are some of the highlights of its activities:

1. The commission took an active part in the formation of a new Working Group entitled “International Committee on Ultrahigh Intensity Lasers” (ICUIL). C16 has been designated as the lead commission for this working group and the chairperson of C16 is an ex-officio member of the Committee. The main charge to the Committee is to provide a venue for discussions among representatives of the Ultrahigh Intensity Lasers facilities and members of the user communities on international collaborative activities such as the development of the next generation ultrahigh intensity lasers, exploration of new areas of fundamental and applied research, and formation of a global research network for access to advanced facilities by users. ICUIL was mandated by the IUPAP Council in October 2003 and has since been very active in organizing a number of events to promote their aims.
2. Individual commission members played an active role at national and international levels in promoting various events and activities related to the International Year of Physics Celebrations. Reports of such events were circulated amongst committee members and various ideas were exchanged.
3. A website for the commission was established at http://www.ipr.res.in/c16iupap/
4. C16 helped in the selection of a member for the Working Group on Energy who could provide the necessary inputs for identifying the energy needs of developing countries and also discuss the potential role of thermonuclear fusion and plasma based technologies in meeting the future energy needs of the world.
5. C16 also contributed a chapter to the book "Physics Now," - a collection of articles for non-specialists, discussing recent developments and the current state of the art in the major areas of physics as represented by the various IUPAP Commissions. The book was produced by Commission 14.
6. The commission made conscious efforts through the initiatives of individual members and their national bodies to ease the situation regarding the delay in granting of visas and the difficulty faced by scientists traveling to the U.S. for conferences and other academic activities.

2. Advances in the field

Plasma physics continues to flourish as an active and exciting field of physics with ever expanding frontiers into novel areas of basic science as well as applications. Below I highlight a few of the important developments in the various areas of the field.

1. Magnetic Confinement Fusion (MCF):
   Tokamaks, the leading magnetic confinement devices, have continued to demonstrate significant progress in the achievement of higher performance parameters (plasma density, temperature, confinement time etc.) and also in gaining a better understanding of plasma instabilities and their control. Recent experiments on JT-60U (Japan) and Torre Supra (France) have achieved long pulse multi-megawatt operations that mark a significant progress towards the goal of investigating steady state regimes in tokamaks. In attaining these performance parameters a host of control issues have been addressed and new insights into particle and heat transport in the presence of rf current drives have been gained. Novel methods of controlling bursty plasma behaviour due to edge-localized modes (ELMs) by using external rf signals have been demonstrated on the D-III-D tokamak (USA). Plasma turbulence studies based on sophisticated fluid, gyro-fluid and particle simulations have also made significant progress and have reached a stage where they can provide excellent interpretation of many experimental results. Stellarators, the alternate leading contenders in the toroidal magnetic configuration category, have also shown a steady and positive advancement in the past few years due to improved performance observed on machines like the LHD (Japan), the Wendelstein series of devices (Germany) and smaller devices like the CIEMAT machine (Spain). In addition to the excellent scientific progress in MCF perhaps the most heartening development in recent months has been the resolution of the deadlock over the decision on the building site for ITER. The concerned parties have now agreed to build ITER at Cadarache (France) and thereby opened up the way for quickly getting to the construction phase of this important and crucial next step for marching towards a demo fusion reactor.
2. Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP).
   Recently the first hohlraum and laser propagation experiments have been performed at the National Ignition Facility (USA) – the most advanced facility that has been built for ICF and HEDP research. For the indirect drive experiments vacuum hohlraums have been irradiated with laser powers up to 8 TW, 1-9 ns pulse lengths and energies up to 17 kJ. Experiments and theoretical research (backed by extensive simulations) carried out at ILE (Japan) show promising prospects for the fast ignition route to ICF and will be further validated when an additional heating laser (10kj/10ps/1.06 mm) becomes available in 2007. There also continues to be dramatic progress in applying pulsed-power to investigate High Energy Density Physics (HEDP) and Inertial Confinement Fusion (ICF). The Z facility at Sandia National Laboratories delivers ~20-MA currents to create high magnetic fields (> 1000 T) and pressures (Mbar to Gbar). The large magnetic pressures directly-drive material dynamics and EOS studies at pressures up to 10 Mbar in Al. Applications of wire-array radiation sources include two different z-pinch driven ICF concepts: the dynamic-hohlraum and the double-ended z-pinch hohlraum (DEH). Progress in achieving radiation symmetry of 2-4% for indirectly driven ICF capsule implosions with the DEH has been reported.
3. Plasma based particle acceleration:
   The past two years have seen some dramatic achievements in the field of plasma based particle acceleration methods. Experiments on the laser wakefield concept and related schemes carried out at various laboratories in France, U.K. and the U.S.A., have demonstrated electron energy gains ranging from 1 Mev to 200 MeV, and creation of accelerating electric fields in the range of 1 GV/m to 1000GV/m. The most striking results pertain to the high quality of the emitted electron beams that have low emittance (less than 3 p mm.mrad) and are nearly mono-energetic. The beams also have significant charge (about a billion electrons). The experiments reveal a new physical regime, in which electrons are ‘self-injected’ in a narrow region of space and surf as a single group, all reaching the same energy. The quality of the beams is comparable to the best of the beams produced by radio-frequency systems. Moreover, the pulse lengths of the beams are about 10 femtoseconds, making them attractive as potential radiation sources for ultra fast time-resolved studies in biology and physics.
4. Space and Astro-plasmas
   Plasma physics continues to gain importance in a variety of astrophysical research areas such as in understanding the origin of cosmic magnetic fields, the formation of accretion disks and relativistic jets, and the dynamics of supernovae explosions. Fundamental studies on magneto-rotational instabilities such as the Balbus-Hawley instability, are receiving increasing attention due to their potential role in understanding transport and turbulence phenomena in the sun and other stellar bodies. The role of charged dust in galaxy and star formation is also being vigorously investigated. Other areas of interest include the formation of electron-positron pair plasmas close to a pulsar and the creation of an outward driven relativistic wind. The study of such ultra-relativistic winds has received a great deal of impetus from integrated observations involving ground-based detections of TeV photons combined with high resolution images in the X-ray (Chandra and XMM satellites) and optical (Hubble Space Telescope) wavelengths. These have revolutionized our picture of these winds and placed strong constraints on dissipation and particle acceleration models. Experimental astrophysics is also being carried out in table top experiments thanks to the advent of compact ultra-powerful lasers (several terawatts) which permit high compression of matter and facilitate simulation of astrophysical phenomena. Interesting EOS studies are being carried out in such experiments.
   
   Space plasma studies continue to address various issues related to the composition and dynamics of the ionosphere, the magnetosphere, their mutual coupling, the solar wind interaction with the magnetosphere, solar seismology and global electric fields. A host of satellite systems and space probes are also helping in the study of planetary atmospheres, comet compositions and cosmic radiation energetics. The Cluster satellites are providing valuable data on the penetration of the solar wind plasma into the magnetosphere and the development of sub-storms which are a major source of concern for power companies in high latitude areas where disruptions to power line supplies can be initiated by sub-storms. The prediction of sub-storms continues to be an important topic of research under the general area of space weather studies.
5. Plasma physics for Industrial applications
   Low temperature non-thermal plasmas have proved useful in a number of applications such as etching and deposition in the microelectronics industry, surface engineering like nitriding and carburizing, plasma displays, waste remediation and pollution control. A host of advances continues to take place in this rapidly developing field which has now a wide base of research centers in university departments and industrial R&D laboratories. Traditionally the non-thermal plasma sources have operated at low pressures but in recent times there has been a great deal of interest in generating such sources at atmospheric pressures. Large area plasma sources operating at atmospheric pressure represent a very cost-effective solution for material processing, light sources and other applications, and a large research effort over the last decade has seen significant progress in this area with the development of Dielectric Barrier Discharges (DBDs) and other similar devices. This has also stimulated basic research in “micro-discharges” and led to interesting insights into the physics and equilibrium configurations of filamentary plasmas. Other interesting applications of such micro-discharges include their incorporation in airfoils to control the transition between laminar and turbulent flows and reduce drag on aircrafts. Medical and other toxic waste remediation through plasma pyrolysis is another application that is fast finding acceptance in industrial as well as developing societies. Industrial plasma research is indeed going through an explosive phase as witnessed by the growth in the number of publications and research journals in this field and also the rise in the number of papers presented in both ICPP and ICPIG.
6. Fundamental plasma science
   The excitement of research in fundamental plasma science continues to be undiminished despite the predominance of large-scale projects in controlled fusion and other major applications. Grand challenge problems such as gaining a detailed understanding of magnetic reconnection or turbulent phenomena in a magnetized plasma are receiving more intensive attention due to the availability of better numerical simulation tools and more sophisticated diagnostic measurements. The field has also benefited from interfacing with other areas of physics and mathematics such as soft condensed matter (for understanding dusty plasma crystals and their collective behaviour), atomic and molecular physics (for understanding laser-cluster interactions), nonlinear dynamics ( for modeling a host of nonlinear phenomena involving wave particle interactions), non-equilibrium statistical mechanics (for getting some insight into plasma turbulent behaviour), fluid dynamics etc. The interchange of ideas and paradigms across such diverse disciplines will continue to energize and engage researchers in basic plasma science for a long time to come.