Why does VASIMIR have a low T/W?
>The technology of advanced high-temperature superconductors has also matured significantly in the last decade with the development of commercially available high current density BSCCO and YBCO conductors by companies such as Superpower Inc. and American Superconductor. These developments have made lightweight, high-field magnets for VASIMR® applications feasible. Moreover, miniaturized cryocooler technology, such as the Sunpower M series model, has already flown in space and are being considered by Ad Astra as part of the cryogenic system for the flight magnet. Ad Astra’s VX-200 test engine features the largest cryogen-free, high-field, low-temperature superconducting magnet in existence today. This magnet was developed to meet Ad Astra’s specifications and has operated quite successfully in the VX-200 engine since its integration in May of 2009. The company is currently designing a high-temperature flight version of this system.>
Okay let me put it this way: why is the power/weight of VASIMIR bad vs. an arcjet?
Robert Zubrin launched into a rant about VASIMR on July 11, 2011 calling it a "hoax" -http://www.marssociety.org/home/press/tms-in-the-news/thevasimrhoaxPhysOrg story from July 13, 2011 -http://www.physorg.com/news/2011-07-zubrin-vasimr-hoax.htmland Ad Astra posted this on July 15, 2011 -http://www.adastrarocket.com/VASIMR_development_AdAstra_15July2011.pdfI found several problems with Zubrin's article including his contention that high temperature superconducting magnets it would find useful do not exist. Ad Astra countered that assertion in their reply -
... In contrast, after 30 years of research, the VASIMR has only obtained about 50 percent efficiency in test stand burns of a few seconds’ duration, and that is only at high specific impulse.
This is the dangerous sentence.Quote... In contrast, after 30 years of research, the VASIMR has only obtained about 50 percent efficiency in test stand burns of a few seconds’ duration, and that is only at high specific impulse.For a 6 month burn the VASIMR needs to thrust for 6 * 32 * 24 * 60 * 60 = 16588800 seconds.It sounds like the current VASIMRs cannot even thrust for a full minute. That definitely needs fixing.
Solar VASIMIR will not move much without panels 10x bigger than on the ISS even with new technology....