Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas Office of Science U.S. Department of Energy ION HEATING: Planning the next steps for the astrophysical case Robert Rosner The University of Chicago Madison, WI Aug. 5, 2004

Ion heating: Planning the next steps for the astrophysical case 2 Lets start by recalling our earlier conclusions In the Solar case, the key issues are Identifying plausible ion heating mechanism(s) and acceleration process(s) Solving the puzzle of creating the required waves Can one obtain a cascade (in both spatial/temporal frequencies), or Are the waves related to observed reconnection and shock event? In the particular extra-solar case discussed, the key issue is Can we find a way of decoupling electrons from protons under cluster/accretion conditions?

Ion heating: Planning the next steps for the astrophysical case 3 What was our plan, earlier this year? In the Solar case, we decided that laboratory studies were the key to better understanding of the ion heating process(es); this is what G. Fiksel has reported on in the absence of identifying the relevant heating process, it would not be productive to focus on mechanisms for generating candidate waves In the particular extra-solar case discussed, we decided that we did not have the resources to attack this problem at present

Ion heating: Planning the next steps for the astrophysical case 4 What is our current thinking? In the Solar case, we believe that the time is ripe to now look in detail at mechanisms for generating candidate waves for ion heating newly-recognized lab-related opportunity (see below) the first case to look at in more detail is the question of how cascades may lead to the requisite waves at short spatial and temporal scales the first step is an experimental look at such possible cascading existing level of theory in the solar context is now ahead of observations the LAPD at UCLA (W. Gekelman) is an appropriate venue for such measurements; we have written a draft white paper to this point To our pleasant surprise, such measurements may also shed light on the astrophysical problem of understanding the spectrum of scintillations - and turbulence - in the interstellar medium (!) S. Boldyrev has been studying this problem area … and will give a short report

Ion heating: Planning the next steps for the astrophysical case 5 … which brings us to QUESTIONS AND DISCUSSION