Significance of Electron Recirculation Revisited
Posted: Sun Mar 28, 2010 6:24 pm
My understanding of the contribution of electron recirculation in the operation of the Polywell is hopefully improved.
I have generally concieved that electron recirculation improves effective electron lifetimes by a factor of ~ 10, based on the 10 X improvement between WB4 and WB6. Thus WB4 has an assumed lifetime of 10,000 transits and WB6 has 100,000 transits before the electron is lost. In a 1 meter diameter wiffleball, and 10,000,000 meter/ second speeds this translates to ~ 1 millisecnd lifetimes for the nonrecirculated electron and ~ 10 ms for the recirculated electron. I'm assuming that the thermalization time is dependant on the unrecirculated lifetime, as recirculation resets the electron to the original energy and direction. In WB6, under these conditions ansd assumptions the unrecirculated electron lifetime would be ~ 0.2 milliseconds (10,000 transits of ~ 0.2 meter wide wiffleball at 10,000,000 m/s)).
But, it occured to me that I was probably assigning the wrong unrecirculated lifetime to WB4. 1000 transit wiffleball traping factors have been mentioned by Bussard, etel. So, 10,000 transits in WB4 actually includes ~ 10X recirculation factor. I had perhaps foolishly ignored this and calculated the lifetime of unrecirculated electrons as 10,000 transits. WB 4 does apparently have significant recirculation occuring, its just that WB6 was 10X better (100X overall) due to the design changes.
Transit lifetimes due to:
WB alone = 1,000
WB + WB4 recirculation = 10,000
WB + WB6 recirculation = 100,000
The significance of this is that the lifetimes of the unrecirculated electrons in a 1 meter machine would be 0.1 milliseconds, rather than 1 millisecond.
This provides only one tenth the time for thermalization to occur and relaxes the restraints on arguments that claim thermalization times exceeds the electrons unrecirculated lifetimes.
Dan Tibbets
I have generally concieved that electron recirculation improves effective electron lifetimes by a factor of ~ 10, based on the 10 X improvement between WB4 and WB6. Thus WB4 has an assumed lifetime of 10,000 transits and WB6 has 100,000 transits before the electron is lost. In a 1 meter diameter wiffleball, and 10,000,000 meter/ second speeds this translates to ~ 1 millisecnd lifetimes for the nonrecirculated electron and ~ 10 ms for the recirculated electron. I'm assuming that the thermalization time is dependant on the unrecirculated lifetime, as recirculation resets the electron to the original energy and direction. In WB6, under these conditions ansd assumptions the unrecirculated electron lifetime would be ~ 0.2 milliseconds (10,000 transits of ~ 0.2 meter wide wiffleball at 10,000,000 m/s)).
But, it occured to me that I was probably assigning the wrong unrecirculated lifetime to WB4. 1000 transit wiffleball traping factors have been mentioned by Bussard, etel. So, 10,000 transits in WB4 actually includes ~ 10X recirculation factor. I had perhaps foolishly ignored this and calculated the lifetime of unrecirculated electrons as 10,000 transits. WB 4 does apparently have significant recirculation occuring, its just that WB6 was 10X better (100X overall) due to the design changes.
Transit lifetimes due to:
WB alone = 1,000
WB + WB4 recirculation = 10,000
WB + WB6 recirculation = 100,000
The significance of this is that the lifetimes of the unrecirculated electrons in a 1 meter machine would be 0.1 milliseconds, rather than 1 millisecond.
This provides only one tenth the time for thermalization to occur and relaxes the restraints on arguments that claim thermalization times exceeds the electrons unrecirculated lifetimes.
Dan Tibbets