Fluctuation studies using combined Mach/triple probe

A probe consisting of two poloidally separated triple probes and a Mach pro be (TMT probe) has been designed and installed on the H-1 heliac to study f luctuations. Mach probes are shown to be sensitive to the fluctuations in t he electron density, electron and ion temperatures, and ion drift velocity. If the ion Larmor radius is much larger than the characteristic probe dime nsion, then the Mach probe is insensitive to the magnetic field. When the M ach probe is oriented such that the two tips are separated radially, it bec omes sensitive to the radial velocity of the ions. A model has been devised to allow the above mentioned time-resolved plasma parameters to be reconst ructed from the data obtained using the TMT probe. One of the important res ults of these studies is that ion temperature fluctuations cannot be neglec ted. (C) 2001 American Institute of Physics.