Design of the SSC linac
The preliminary design of the 600-MeV H/sup -/ linac for the Superconducting Super Collider (SSC) injector is described. The linac must provide a 25-mA beam during 7-35 mu s macropulses at 10 Hz within injection bursts. Normalized transverse emittances of less than 0.4 pi mm-mrad (RMS) are required for injection into the low Energy Booster (LEB) synchrotron. Cost, ease of commissioning, and operational reliability are important considerations. The linac will consist of an H/sup -/ source with electrostatic low-energy beam transport (LEBT), a 2.5-MeV radiofrequency quadrupole (RFQ) accelerator, a 70-MeV drift-tube linac (DTL), and 530 MeV of coupled-cavity linac (CCL). The RFQ and DTL operate at 428 MHz and the CCL operates at 1284 MHz. A modest total length of 143 m results from the tradeoff between cost optimization and reliability.<<ETX>>
Design studies of SSC coupled cavity linac
The SSC (Superconducting Super Collider) coupled cavity linac (CCL) will be a side-coupled structure operating at 1284 MHz to accelerate a nominal 25-mA H/sup -/ beam from 70 MeV to 600 MeV. Results of both cavity design and beam dynamics studies are presented. Each accelerating cavity is optimized by SUPERFISH; coupled cavity characteristics in the region of low-, mid-, and high-energies are checked by MAFIA-3D. MAFIA-3D was also used to design the bridge coupler systems. The beam dynamics and error analysis are simulated by CCLDYN and CCLTRACE. Possible future upgrading of the CCL to 1 GeV is also discussed.<<ETX>>
Atmospheric drag effects on the KOMPSAT-1 satellite during geomagnetic superstorms
We examine the atmospheric drag on the low earth-orbiting satellite, KOMPSAT-1 in a sun-synchronous orbit at ~685-km altitude starting in 1999, during a 3-month (October-December) period in 2003. This 3-month interval includes the October 29-30 and November 20 magnetic superstorms and weak to moderate storms. We observed that the daily KOMPSAT-1 drag acceleration transiently responses to transient storm-time disturbances. That is, there is an one-to-one correspondence between the KOMPSAT-1 drag accelerations and the storm events. We find that the drag acceleration correlates strongly with the level of geomagnetic disturbance. This indicates that the trajectory of KOMPSAT-1 is significantly perturbed during extremely disturbed intervals because of atmospheric density increase. The main contributor to the density increase is Joule heating associated with the geomagnetic activity rather than the solar EUV radiation, as reported by previous studies. We suggest that understanding how the upper atmosphere responses to the geomagnetic-associated heating is important to predict space weather impacts on low earth-orbiting satellites.