Question about RFQ error

[msh3069]

Dear Toutatis members

First, I write down the topic at TRACEWIN forum but it is more relevant to Toutatis so I write down at here again.

Thesedays I start to work on RFQ error study in TRACEWIN with Toutatis.

Then I have question about the tilt error. At the manual, it says that the tilt error is defined with ''mm'unit not a "degree" or "radian" unit.
Therefore, I want to check whether I correctly understand.

1.
For example, if the longitudinal length of the electrode is 1m and if I want to give 0.1 degree of tilt angle then should I set the tilt set up to 1*tan(0.1 degree)?

2.
If the RFQ is 4-vane type and If I set the TEpe as 100um maximum value. then does the TRACEWIN generate the 4 error values for each electrode?
for example, (26um for electrode 1, 20um for electrode 2, 30um for electrode 3, 10um for electrode 4)

Best Regards

SeokHo Moon

[msh3069]

Sorry for the many question, I have one more question.

At the toutatis we can define the longitudinal profile error and RF phase error.
1. Does the longitudinal profile error means the error at 'a' at the attached figure?
2. Does the RF phase error corresponding to the error at 'L' at the attached figure?

Best regards

[RomualdDuperrier]

Hi

I will try to respond to your requests one by one:

1. For example, if the longitudinal length of the electrode is 1m and if I want to give 0.1 degree of tilt angle then should I set the tilt set up to 1*tan(0.1 degree)?
RD: the axis for the tilt is at the middle of vane, thus tan(alpha) = d * 2/L where L is the vane length and d the resultant transverse shift at the extremity. With your example, you should write d = tan(0.1°) * 1/2

2.If the RFQ is 4-vane type and If I set the TEpe as 100um maximum value. then does the TRACEWIN generate the 4 error values for each electrode?
for example, (26um for electrode 1, 20um for electrode 2, 30um for electrode 3, 10um for electrode 4)
RD: Toutatis generates random errors set for each vane, then yes, it will be 4 error values. It is true whatever the electrode type (rod or vane).

1. Does the longitudinal profile error means the error at 'a' at the attached figure?
RD= Longitudinal profile error will induce a shift between the extrema of an electrode. In other words, minimum a will not be at the same location z than the maximum mxa for the neighboring electrodes. Note that the new GUI for Toutatis 2.0 helps you visualizing the different errors (.inp editor).

2. Does the RF phase error corresponding to the error at 'L' at the attached figure?
RD: No. It is a random error dPhi on V/2 x sin(omaga x t) => V/2 x sin(omaga x t +dPhi) for the polarization of the electrodes. It is more then a way to simulate phase errors with your power supply ou LLRF.

I hope it helps,

Romuald

[msh3069]

Thanks for the kind reply, I understand your answer about first two questions.

However, there are remained unclear things for me. It is about question 3, 4.

3. Question about longitudinal profile error
Does it means that the value of a is not changed but the the z position for the maximum pole is changed?

4. Question about the field phase error
The RFQ can be think as single cavity so does the random error dphi means that the error of input RF?
Then it looks like the rf phase error set to all of the RFQ cells equally.
Does I correctly understand?

Best Regards

SeokHo Moon