Simultaneous observations of explosive chromospheric evaporation are presented using data from the Reuven Ramaty High Energy Solar Spectroscopic Imager ( RHESSI ) and the Coronal Diagnostic Spectrometer ( CDS ) onboard SOHO .
For the first time , co-spatial imaging and spectroscopy have been used to observe explosive evaporation within a hard X-ray emitting region . RHESSI X-ray images and spectra were used to determine the flux of non-thermal electrons accelerated during the impulsive phase of an M2.2 flare .
Assuming a thick-target model , the injected electron spectrum was found to have a spectral index of \sim 7.3 , a low energy cut-off of \sim 20 keV , and a resulting flux of \geq 4 \times 10 ^ { 10 } ergs cm ^ { -2 } s ^ { -1 } .
The dynamic response of the atmosphere was determined using CDS spectra , finding a mean upflow velocity of 230 \pm 38 km s ^ { -1 } in Fe xix ( 592.23 Å ) , and associated downflows of 36 \pm 16 km s ^ { -1 } and 43 \pm 22 km s ^ { -1 } at chromospheric and transition region temperatures , respectively , relative to an averaged quiet-Sun spectra .
The errors represent a 1 \sigma dispersion .
The properties of the accelerated electron spectrum and the corresponding evaporative velocities were found to be consistent with the predictions of theory .