QUENCH DESCRIPTION BY THE CHARACTERISTIC TIME CONSTANTS

The problem of a quench consequences of superconducting windings is co nsidered. Inherent features of a quench behavior can be described by t hree characteristic time constants: 1) the normalization time t(n) whe n normal Bone would propagate over all winding volume provided transpo rt current I-0 is kept constant, 2) the time of the current decay ti p rovided the winding resistance Ro is kept constant, and 3) the time of current decay t(e) due to an external dump resistance R-e. In a simpl e model where the normal zone velocities in longitudinal and transvers e directions are proportional to the decaying current, a quench behavi or (hot spot temperature, maximum internal voltage and stored energy e vacuation efficiency) is analized in dimensionless form depending upon the dimensionless time constants tau(i) = t(i)/t(n) and tau(e) = t(e) /t(n). It is shown that the active protection is efficient only if tau (e) < 1. In the absence of the active protection (tau(e) = infinity), for magnets with tau(i) < 1 the overheating is dangerous, while for th ose with tau(i) > 1 the internal voltages are dangerous. These results are confirmed by numerical examples which also show that the normaliz ation time t, is the most important parameter in the description of qu ench behavior.