Solenoid design
Solenoid design
(OP)
Hi all!
I would like an advise about how to choose the proper dimensions of two solenoids:
I would like to have them with air core, internal max diameter 4 mm, external max diameter 8mm, maximum length 2cm.
Now: these solenoids are going to be operated at 30kHz sinusoidal current so the diameter of the wire should be thin enough not to present a big skin effect but big enough to carry quite a lot of current.
The aim is endeed this:
I would like to put two solenoid (aligned on their axis) with a gap of 2.5cm between the two opposite faces (as they were a singol solenoid splitted in two parts with some distance in between)
I would like to have 50 gauss peak magnetic field in the gap between the two part of the solenoids..
Can you help me to understand if this is feasible and how to calculate the current I need?
I would like an advise about how to choose the proper dimensions of two solenoids:
I would like to have them with air core, internal max diameter 4 mm, external max diameter 8mm, maximum length 2cm.
Now: these solenoids are going to be operated at 30kHz sinusoidal current so the diameter of the wire should be thin enough not to present a big skin effect but big enough to carry quite a lot of current.
The aim is endeed this:
I would like to put two solenoid (aligned on their axis) with a gap of 2.5cm between the two opposite faces (as they were a singol solenoid splitted in two parts with some distance in between)
I would like to have 50 gauss peak magnetic field in the gap between the two part of the solenoids..
Can you help me to understand if this is feasible and how to calculate the current I need?





RE: Solenoid design
First calculate the B along axis of one solenoid (easily google it to know how). For two solenoid (aligned wiht axes), the field B can be calculated by using half of distrance (i.e. 1.25cm).
vice versa, when you need B= 50 Gs, you can re-calculate the needed N.A
RE: Solenoid design
RE: Solenoid design
RE: Solenoid design
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Plymouth Tube
RE: Solenoid design
RE: Solenoid design
I recommend using powder core with tens of permeability even at a oprn circle. here is a link telling oyu how to choose powder core materials and how to design circle.
RE: Solenoid design
RE: Solenoid design
And what do you mean with tens of permeability at open circuit??
So finally the ratio between core and gap field is really high..what about optimizing the geometry so that this ratio goes down? Do you think would be an improvement using the Helmoltz configuration? Not sure I ave enough space to build both of the solenoids with 1" inner diameter, but one for sure..
RE: Solenoid design
tens of permeability: assuming permeability = 10, you just need H filed of H = 1000 Oe to generate a B field of 10,000Gs. If you use air coil (perm =1), you will need a H filed of 10,000 Oe to generate a B of 10,000Gs. That basically saves your N.A (ampere turns) 10 times.
RE: Solenoid design
I have probably already saw that link but I will double check it for sure, thanks!
Ps any comment about the geometry?
RE: Solenoid design
increasing diameter or length of solenoid can help. for example, For two solenoids with L=2cm, ID = 8 mm, at the air gap of 2.5cm, you just need about 2600 G field in the solenoid to generate a B of 50G. you may use ferrite now.
RE: Solenoid design
Wow, that's great, do you have an analytical relation between ID and ration between core and air gap or you're using a software? If I know what you're using I can perform a parametric study on that and find out the optimum ID or even try to understand how the solenoid length affects that ratio (stopping in this way to ask un million single questions eheheh)
RE: Solenoid design
So now the problem is to design a solenoid able to produce 50G on his axis at 1" distance.
I found that with 1mm diameter wire and 2A (hoping it's not too much for the wire (it's going to be in vacuum)) I need 20x20 turns-> a lot...
And since they're going to be operated at 30khz I'm worried about proximity effect (I'm going to have 20 layers of windings..) not sure if Litz wire can help to reduce this..and not sure if you suggest me using bigger section with more current and less turns or something else (to me it seems that with less layers the field is going to spread quicker outside of the solenoid..
I'm also tring to find a power supply able to give power at 30khz, probably 3A max, not sure about the Voltage, it seems to be the impedance is going to be quite high at that frequency..
At this point I may also need a matching network..
I tought it was easier to build and drive a solenoid at 30khz with a peak B field of 50G at 1" ....
RE: Solenoid design
RE: Solenoid design
Problem is also the impedance of this inductor, i'll probably need a matching network otherwise the power supply is going to be damaged or not going to work good...