[Dsg-rtpc] RTPC Valve panel revision - added target and cathode purge gas supply - see attachment

Thu Aug 9 14:43:52 EDT 2018

Looks good to me, thank you! Would it be possible to switch the bottom row with the top row so the Buffer volume  lines are together? Just a nicety, not absolutely necessary.

Greetings - Sebastian

> On Aug 9, 2018, at 1:35 PM, George Jacobs <jacobsg at jlab.org> wrote:
> 
> Hi Sebastian,
> 
> Please find the attached valve panel diagram with updated nomenclature. Let me know if I missed anything or if you want anything changed. 
> 
> Moving to the P&I. I will incorporate the same nomenclature on this as well.
> 
> Cheers,
> George
> 
> On 8/9/2018 12:01 PM, kuhn wrote:
>> Dear George and all,
>> 
>> We may need to clear up our various nomenclature so we understand exactly what each of us is talking about. For instance, in the new gas panel plot you sent, there is a line “from target” going through a “target bubbler” to “exhaust to ATM". However, “the target” is the 6 mm diameter straw that will contain 7 atm of deuterium gas, which is definitely NOT what you are referring to (the whole gas system for the target is a separate system being designed by a different group of people and will have of course much more stringent pressure vessel requirements.)
>> 
>> The only thing THIS gas panel is supposed to take care of is
>> a) the drift gas mixture 4He/CO2 that gets supplied to the RTPC (which, as I pointed out, internally funnels it through both the “ground to cathode” stand-off volume AND the drift+GEM amplification volume). From the point of view of the gas panel, that’s a single line in and a single line out.  However, to control the detector parameters we need this same gas to also flow through the DMS - either in parallel or in series. Plus we need extra lines to measure the pressure in both the RTPC and the relative pressure in the DMS. This seems to be addressed by the present plan.
>> b) There is a “buffer volume” surrounding the target itself and extending to the inner radius of the RTPC (the ground foil). We need a separate gas supply line, a pressure measurement and an exhaust for this volume.
>> This is neither “from target” nor a “purge gas supply”, but simply “buffer volume supply” and “buffer volume exhaust”, but the needed functionality could be taken over by the lines labeled such on the diagram (maybe we should group them together?)
>> This buffer volume could either be filled with 4He or with the same 4He/CO2 mix as the RTPC. However, your suggestion to just use the existing Hall B 4He gas supply makes the second option unnecessary in my opinion, so my preference would be to use 4He.
>> 
>> In any case, we need to make sure that we label everything on both the drawing and the actual gas panel as clearly and unambiguously as possible, to avoid any confusion by the operators.
>> 
>> Thanks - Sebastian
>> 
>> 
>>> On Aug 9, 2018, at 10:46 AM, George Jacobs <jacobsg at jlab.org>
>>>  wrote:
>>> 
>>> Hi Sebastian,
>>> 
>>> Hall B has a He4 gas supply system with connections available on L1 space frame.  If you prefer He for the purge, it's a simple matter to run a line to the valve panel from the supply header. 
>>> 
>>> Do you want an absolute or differential pressure transducer for the target purge volume? I have placed an absolute Baratron on the valve panel diagram. See attached valve panel diagram.
>>> 
>>> Cheers,
>>> George
>>> 
>>> On 8/9/2018 9:14 AM, kuhn wrote:
>>> 
>>>> Just for clarification: The region between ground foil and cathode is INTERNALLY connected to the drift region (inside the RTPC itself). The slight overpressure we were talking about can be achieved by properly dimensioning that internal connection and the gas flow. So all we need is 2 gas lines for that inner volume (split from a single gas line) and a single exhaust gas line from the RTPC.
>>>> The question about the buffer volume (between target and ground foil) is separate. Originally we wanted to use pure 4He for that buffer region. Recently, we have considered using the same gas mix (He/CO2) just to simplify the setup. But in any case this needs a separate inlet and outlet gas line, with bubbler, pressure sensor, and flow meter.
>>>> 
>>>> Sebastian
>>>> 
>>>> 
>>>> 
>>>>> On Aug 9, 2018, at 8:36 AM, George Jacobs <jacobsg at jlab.org>
>>>>> 
>>>>>  wrote:
>>>>> 
>>>>> Hi Carlos,
>>>>> 
>>>>> Correct and correct. It's best to split the target and cathode purge gas as close to the RTPC connections as practical.
>>>>> 
>>>>> Cheers,
>>>>> George
>>>>> 
>>>>> On 8/8/2018 5:58 PM, Carlos Ayerbe wrote:
>>>>> 
>>>>> 
>>>>>> Hi George, 
>>>>>> 
>>>>>> thank you very much. Just to be sure that there is no confusion from my side. 
>>>>>> 
>>>>>> - "To RTPC" is the line to the drift region, which we were always working. This line is 1/2", correct?
>>>>>> 
>>>>>> - "To Target and Cathode Volumes" are the lines to the regions we discussed today. It is one line in the scheme, but it is split in two afterwards, isn't it?. Also, they are 1/4", correct?
>>>>>> 
>>>>>> Thank you
>>>>>> 
>>>>>> -Carlos
>>>>>> 
>>>>>> ----- Original Message -----
>>>>>> From: "George Jacobs" 
>>>>>> 
>>>>>> 
>>>>>> <jacobsg at jlab.org>
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> To: 
>>>>>> 
>>>>>> 
>>>>>> dsg-rtpc at jlab.org, "Carlos Ayerbe-Gayoso (gayoso at jlab.org)" <gayoso at jlab.org>
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> Sent: Wednesday, 8 August, 2018 17:07:32
>>>>>> Subject: RTPC Valve panel revision - added target and cathode purge gas supply - see attachment
>>>>>> 
>>>>>> Hi Carlos, 
>>>>>> 
>>>>>> Please find attached pdf 
>>>>>> 
>>>>>> I have added the gas supply for the purge of the target area and the cathode ( middle) volumes along with the bubblers for each. 
>>>>>> 
>>>>>> I will have the P&I diagram revision completed in a couple days. 
>>>>>> 
>>>>>> Cheers, 
>>>>>> George 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>> -- 
>>>>> George Jacobs
>>>>> Jefferson Lab (TJNAF)
>>>>> STE 12
>>>>> 12000 Jefferson Ave.
>>>>> Newport News, VA 23606
>>>>> 
>>>>> (office) 757-269-7021
>>>>> 
>>>>> (cell)   757-876-0480
>>>>> 
>>>>> (email) 
>>>>> 
>>>>> 
>>>>> jacobsg at jlab.org
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> (website) 
>>>>> 
>>>>> 
>>>>> https://userweb.jlab.org/~jacobsg
>>>>> 
>>>>> 
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>>> -- 
>>> George Jacobs
>>> Jefferson Lab (TJNAF)
>>> STE 12
>>> 12000 Jefferson Ave.
>>> Newport News, VA 23606
>>> 
>>> (office) 757-269-7021
>>> 
>>> (cell)   757-876-0480
>>> 
>>> (email) 
>>> 
>>> jacobsg at jlab.org
>>> 
>>> 
>>> 
>>> (website) 
>>> 
>>> https://userweb.jlab.org/~jacobsg
>>> 
>>> 
> 
> -- 
> George Jacobs
> Jefferson Lab (TJNAF)
> STE 12
> 12000 Jefferson Ave.
> Newport News, VA 23606
> 
> (office) 757-269-7021
> 
> (cell)   757-876-0480
> 
> (email) 
> jacobsg at jlab.org
> 
> 
> (website) 
> https://userweb.jlab.org/~jacobsg
> <RTPC-ValvePanels-8-9-2018-rev3.pdf>