Particle accelerator engine - How to develop into a working model?

chat · 2003-10-30 07:08:10

Eurler has been working out some of the math on my particle accelerator engine idea, and helping me get a better idea of needed thrusts, mv power requirements and fuel.

If you need more information on the idea please look at (reason for rubber ball) on this forum.

How do we go about developing this idea further?
And how about some input from the critics as to why it won't work?
Also the slow acceleration problem for traveling in our solar system needs more work, i had a simple but complex tech solution to it.
It's going to need to accelerate much faster if it's going to be useful in our solar system for human travel.
I bet an easier solution exists than 17 acceleration tubes.?

Everyone please feel free to dive right in here

Nick

John B · 2004-01-23 22:55:44

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Currently in use commercial and reasearch particle accelerators are very energy inefficient dc power is converted to rf power with about a 60% effeciecy no effort is made to use superconducting technology on either the accelerating cavities or the steering magnetics. In a space ship you would want to make the RF source for the accelerating wave guide operated by your fuel ions as well as their electrons Since vacuum is free you would use large vaccum full wave rectifier and capacitve ladders on your combo ion injection gun cum positive ion klystron rf generator you would shoot for multi megaohm rf mpedances on your guide, but it would stiil be very dificult to bring positive ions even H+ up to anything near a cv section on that accelerator. epecially since you would need tens of thousands of amps average beam current--- needless to say you would need a big nuclear reactor and waste cooling radiator to power all this. It would weigh a lot even if you used superconducting magnets and current carriers on the generators and kept the system as cold as possible(under 800c) to minimize waste heat, the turbine would have to be extremely largeto eliminate a monstrous condenser indeed you would most probably have to use the bulk of the ships hull surface for waste heat radiation esepcially during engine and reactor shutdown when the turbine is not turning the heat into power. you would need in space docks at both ends of the "run" just to utilize the cool down power and provide an ECCS and shielding for debarking and embarking passengers and for maintenance workers who would use hydraulic robots for the actual work. a nuclear submarine probably provides the best model for the type of power plant required. with the caveat that there is no nearby free source of coolant or umlimited thermal mass to get rid of unwanted heat, --One who spent 11 years doing this stuff

chat · 2004-01-26 20:02:33

Hi John B,

And thank you for your input.
It's nice to see that I'm not the only person working on this idea.
Sometimes it feels a little like it's such a crazy idea that it might just work *lol*

I agree that current accelerator technology is more that efficient enough to supply the needed thrusts to obtain decent percentages of c.

And as you point out the amperage needed for a beam of sufficient %c is already there in nuclear subs.

I bet you've done the calculations of down sizing the accelerator to conserve power.?

I've played with a few of these calculations, and it seems that making a vastly smaller accelerator for a space ship only shows limited savings in power requirements.

The best power to thrust to weight i get, seems to be about a 1/2 to 1/3 scale accelerator.
At 1/2 scale it produces about 80% the speeds of a full scale accelerator, but only requires about 60% of the power.
Also a 1/2 scale accelerator is within reasonable limits to get into space.

As you've pointed out it's going to have to be a nuclear powered vehicle.
The needed power for the accelerator to be viable is a minimum of 25mw, and 50mw or more would be a much better number.
Cooling the reactor is quite a simple process. (semi simple)
Coolant can be cycled in shaded radiators outside the spacecraft, or as you said you can use the bulk of the hull to cool waste heat.

I don't see this as being a vehicle that carries any humans.
It's going to be a nasty environment that would require many safeguards for human travel.
Although it will have a very friendly gama ray and solar flare deflecting magnetic field from the accelerator, it will also be carrying a full scale nuclear reactor, fuel rods etc in a vibrating pulsing machine that is guaranteed to have a host of small hick ups.
Also it's going to be a very slow acceleration vehicle, similar to deep space.
It will get going at very high speeds, but i don't think in relative human terms for solar system travel.

It might be a great robot vehicle that takes pictures of the outer planets, drops probes, and continues on as it speeds up to visit a near bye star.

It seems to come down to this.
1. It needs to be a pretty decent sized accelerator.
2. It needs a minimum of 25mw power.)(nuclear)
3. It needs many tons of particle accelerant as thrust.
4. It needs a vast coolant system to keep the reactor from over heating.
5. It needs a gigantic effort in R&D to solve escaping particles causing a beam shutdown or worse.

Any one of these is a huge space or R&D project.
But all put together i think would require such a vast amount of money and resources, that it would require a world wide effort to create a project to send probes to the stars.
But it does point to the fact that if we wanted to send probes to the stars, it's something we could do now.

And with just a few 100 billion dollars

Nick

John B · 2004-02-18 18:32:03

i am not sure what the last poster means by a 60 % size reduction in a proton linac type particle accelerator. The problem with any other particle than an electron is as the speed changes during acceleration the length of the resonating structure must also change to keep all nuclii within 90 degrees phase of the acceleating voltage otherwise you cease to accelerate and instead decelerate since out of phase beam current losses both drop the impedance on the guide thus loading the rf and become waste heat, when you are talking about power levels that can vaporize any material in microseconds you must have design efficiency in the sense of capturing and accelerating the entire beam current "Fish" including inherant design features that will both bunch a lagard tail and disgcourage radial ion travel ( usually magnetics for this last) The only advantage that a non CV (Constant Velocity or greater than 99% C) accelorater has is that it makes it easier to eliminate in phase radial oscillations gaining in magnitude and thus contributing to parasitic power losses in the form of so called "Synchrotron Radiation". everywhere else it is a nightmare because the acceleration velocity gained by the beam at each stage must precisely match the both the overal mechanical length and the energy input to that stage. in practice it means the rf power must be ramped up as a fixed function of the beam current to maintain beam phase, assumming the extremly high "guide" impedance decrease vs beam current is virtually constant. If impedance has to vary agreat amount because of increased beam loading the guide will have negative stability and loss of phase synchronization thus the system will be unworkable. Also due to the extremely high (3 megaohm plus) overall impedance of the guide section the I squared R losses must be kept lower than even a pure copper surface can do. Therfore the resonating cavities and power coupling lines will have to be plated with superconducters
During the Eighties New England Nuclear tried to build an proton linac with a couple of milliamps beam current at 30 Mev and could not do it. Commercial medical and industrial linacs are all electron and the electrons get up to effective Constant velocity at under a hundred KV so actually the bunching cavity is nothing more than a half cavity on the beginning of the Guide . Bunching losses of a few micro amps at a hundred KV can be ignored Proton bunching losses of even 1 % are significant when you are talking 3 million volts at ten thousand amps, and consider you are going to need voltages like that to set up a strong enough electrostatic field, at a fairly wide accelerator drift tube appature neccesary to contain a proton beam of that high current. What it adds up to is about a half a liter/sec of H+ at STP and at say a 10 cavity machine using about a 25 megahertz frequency. The reasonant length would make the end cavity a toroid with a 1 meter gap and an overall thickness of about 1 meter with a half meter drift tube diameter and a 2and 1/2 meter inside diameter. that would still give beam densities about a hundred times more intense than the most powerful comercial proton cyclotron in use Today.(because of electrostatic forces within the beam this may be not possible.) Even with using only ten cavitieis the injector and resonant accelerator would still be about fifteen meters long. The overall "push" would be about twelve and a half metric tons utilizing only 43 kilograms of propellant fuel (H2) a day. If you could keep the overall weight down of the space craft down to 125 metric tons that would give you a constant one tenth g acceleration making the mars trip ( acceleration and deceleration) in less than twenty days at closest approach. That would mean two things. One you could send the supplies for a mars mission in a 1250 metric ton unmanned fregher with the same power plant about eight months ahead of time and since the life support in the crew pod would be minimal send the people in the smaller 120 ton machine. The interesting thing about this technology is that there does not have to be to much more developemental refinement on either the 50 megawatt reactor or the linac design except for the buncher .
One should note that this is not eficeincy in any sense of the word the total energy expended to accelerate a mass of 1/2 gram per second to ~25% C should only be about 156 kilowatts if all energy was used with total efficiency. We are using 50 megawats of thermal to give us a little more than 30 megawatts electrical, Would any Varian engineers like to weigh in(annonamously or otherwise) at this point ---John

chat · 2004-02-24 05:42:48

Hi John,

I was referring to the weight reduction in the accelerator as soon as it goes into space.

A near perfect vacuum that lowers amperage requirements and causes less beam wandering, super conducting magnets that require no liquid nitrogen to keep them cool, no beam collisions in the chamber etc etc.

All the cheats that a space based accelerator gets for free should allow for a pretty good weight and size reduction, without much impact on the way the accelerator works.

In theory the power required on earth based accelerators should do the same work in a space based one, with 60% to 80% of the power.

Love the 10 cavity idea.
I proposed a similar idea on this board to try and work around it being a very slow acceleration vehicle.
It seemed the most logical way to get it moving fast in much shorter times, and made for a very good mars return vehicle.

Hopefully someone will post about the 156kw.
If that is all the power it needs I'm getting my socket set out and starting to build

Nick

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#1 2003-10-30 07:08:10

Re: Particle accelerator engine - How to develop into a working model?

#2 2004-01-23 22:55:44

Re: Particle accelerator engine - How to develop into a working model?

#3 2004-01-26 20:02:33

Re: Particle accelerator engine - How to develop into a working model?

#4 2004-02-18 18:32:03

Re: Particle accelerator engine - How to develop into a working model?

#5 2004-02-24 05:42:48

Re: Particle accelerator engine - How to develop into a working model?

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