On 12/20/06, Stephen A. Lawrence <[EMAIL PROTECTED]> wrote:
Do you mean reduce resistance?
For a given voltage the time for the current to rise to 67% of its steady state value is given by L/R. Since I must achieve a certain current to achieve a certain magnetic field strength of the electromagnet, the rise time is essentially wasted duty cycle. If I am duty cycle limited, I want to minimize the rise time. The obvious way is to raise the voltage; but, I don't want to exceed 0.5 times the break down voltage of the insulation. As Jones points out, I could use a different core; but, the super permalloy (aka spermalloy :-) being used is probably the best choice. I think we've decided that the least expensive approach for now is to use solid CO2 to increase the duty cycle of the EM by pulling out any heat generated by the coil. (BTW, Jones, virtually every local supermarket sells dry ice these days.) Besides, the condensing water vapor will give the whole test rig that mad scientist look. :-) Ironic that one of the goals of a magnetic motor is to reduce greenhouse gas emissions, however. Terry
