Joseph Chikva wrote:KitemanSA wrote:Joseph Chikva wrote: Despite to instabilities lifetime of plasma in TOKAMAKs reaches minutes. Please note me the lifetime of olasma in "more stable" Polywell.
100% of the drive voltage time. Since the drive voltage time has been pulsed at ~ a millisecond...
And if you would have not pulsed drive voltage but constant high voltage source lasting several seconds or longer? Can you confine plasma in "more stable" Polywell such a long time in that case?
I know that there is not such nessesity but nevertheless please answer if Polywell is really more stable as here mentioned.
Joseph you aqre mixing terms and ignpring the triple product, the most basic consideration for profitable fusion. The confinement time is completely meaningless without density and temperature considerations. A nuclear bomb has very short confinement times, but...
In the Polywell, you first have to reconize that electron confinement and ion confinement are much different. You also have to take into account the claimed lack of thermalization in the Polywell. This implies that at the same average temperature the bulk of the ions in a Polywell have much more favorable fusion crossection chariteristics. This may increase the fusion rate by upto at least an order of magnitude. It also effects thermalization times, etc.
In any case, my understanding of the electron confinement times in a smapp Polywell with modest B fields is ~ 0.2 milliseconds. With recirculation this may be effectively ~ 2 milliseconds. The ions may have confinement times several orders above this. One number I have seen is ~ 20 milliseconds. These numbers are derived from steady state conditions. The actual tests were on the order of a few milliseconds, and numbers were derived from these data.
The densities for Tokamaks I have seen is ~ 10^19 to 10^20 charged particles per cubic meter and target confinement times of ~ 800 seconds. The Polywell densities have been quoted as up to ~ 10^22 charged particles per cubic meter. In short the density in the Polywell may be ~ 100 to 1000X times higher than a Tokamak. Note that the fusion rates will proceed at ~ the square of the density. This equates to ~ 10,000 to 1,000,000 X the fusion rate in the Polywell vs a ITER type Tokamak. 0.2 , or actually ~ 2 millisecond effective confinement time of the electrons in the Polywell multiplied by the density dependant fusion rate difference results in a relative comparative confinement time of ~ 20 to 2000 seconds for the Polywell . If the data is acurate these seemingly short confinement times are perfectly adiuate.
And this is before considering thermalization issues and convergence issues. If 800 seconds is enough for ITER then ~ 1 to 10 milliseconds (for the electrons) is enough for the Polywell. This is a simple comparison of the nessisary Lawson (Triple product) consideration for these two machines.
Of course the issue of the the temperature is also telling. Tokamaks seem to be limited to average temperatures of no more than 5-20 KeV, with most of the fusion occuring in the small high energy thermal tail. This implies that D-T fusion is the only possible fuel for the Tokamak unless they can make a breakthrough in density- tolorable Beta or in the thermal performance. The base target of D-D fusion for Polywell reflects the potential advantages in the density- Beta and thermal advantages.
Dan Tibbets
To error is human... and I'm very human.