Table of contents

Multi-stage dry vacuum pump Ebara A70

Ebara A70W is a multi-stage dry pump from the second generation of dry pumping solutions introduced by Ebara. It has a compact design and includes various sensors and controls. The A70W features a dry pump and a blower, both based on a tri-lobe rotor design.

Scroll pump Edwards xds35i

XDS scroll pumps have become industry standard when dry pumping is essential, proving to be a robust and clean vacuum pump solution in a range of applications and processes. Its bearing shield separates process gases and bearing lubrication to ensure clean vacuum and no possibility of contamination to lubrication from process gases, which prolongs bearing life. The smart motor drive feature comprises consistent performance globally, pump overload protection and remote start/stop capability. The high flow gas ballast allows pumping of vapors including water vapor at up to 240 g/h. The simple single sided scroll design allows maintenance to be done in minutes for low cost of ownership and maximum up-time.

Performance

Dimensions

Turbo pump Varian TV-2KG

The high-throughput turbomolecular pump, Turbo-V 2K-G, is a dedicated vacuum pumping system offering 1600 L/s pumping speed. The Turbo-V 2K-G is designed for industrial use specifically as a turbo pump for thin film deposition equipment. Its pumping stages, and the entire pump structure, are optimized to work with very high flows of argon under high temperature load.

Performance

Dimensions

Overview of the pumping control system

Default setup of the pumping system

MEC's pumping system is comprised of 2 multi-stage dry vacuum pumps (Ebara A70) located on the mezzanine above the hutch, and 2 turbo pumps (Varian TV-2KG) backed with a scroll pump (Edwards xds35i). The following sketch shows the vacuum system as displayed in the controls window.

MEC vacuum system control diagram

The dark grey rectangle in the center symbolizes the target chamber and displays the readout values of different vacuum gauges measuring the in-chamber pressure (top: cold-cathode, bottom-left: pirani, right: capacitance). Let's note that the capacitance gauge is out of order and displays incorrect values.

The top right side of the window details the primary pump subsystem. The ends of this branch lead to the 2 Ebara pumps. Controllable gate-valves are positioned at the target chamber entrance to isolate the primary pump subsystem, at the inlet of each independent Ebara pump, and along the line to allow for venting of the subsystem. Pirani gauges are also used to monitor the pressure along the subsystem pumping line and at the inlet of both Ebara pumps.

The bottom side of the window details the secondary pump subsystem. It comprises 3 branches: 2 of them are identical and symmetric on the sketch, and 1 of them (left-most), the shortest one with only 3 symbols in a straight one, is obsolete. The 2 indentical branches each contain a Varian turbo pump and a scroll pump. The chamber is isolated from these subsystems by a gate-valve, a second gate-valve is used to isolate the turbo from the scroll when the system is shut down. A pirani gauge monitors the quality of the backup pressure provided by the scroll pump.

Finally, the top left side of the windows helps control the venting valves. There are 2 independent venting valves: one supplies compressed dry air (CDA) to initiate the venting procedure, the second one simply opens the chamber to the ambiant atmospheric air (Atm).

Current modifications in the pumping system

MEC has recently experienced a turbo pump failure. As a consequence, we are operating the pumping system with the following structural modifications. The primary vacuum subsystem and the venting valves are unchanged. The modifications are at the bottom side of the window with the failed turbo pump in a "Disabled" status and a backup turbo pump (Maglev) positioned in the formerly obsolete left-most branch.

MEC vacuum system control diagram with the current temporary modifications

The target chamber is in a secondary vacuum state on this sketch. The primary subsystem is vented and the maglev (gate-valve TC1-VGC-01 open/green) is pumping the chamber which reached 2.0e-04 Torr on the cold-cathode gauge (the pirani gauge reached its lower readout limit). The Varian turbo branch (gate-valve TC1-VGC-02 closed/red) is not activated yet, but the turbo is accelerating after startup as shown by the yellow circle.

The procedure presented on this page will explain how to operate the primary vacuum subsystem and a branch of the secondary vacuum subsystem when running with a Varian turbo pump. The Maglev pump is a temporary solution for experiments needing high-quality vacuum, most of our beamtimes run with only one Varian.

Nomenclature of the vacuum system components

List of PVs associated to the vacuum system components

Pumps

Gate-valves

Logical permissions on the gate-valves 

Pressure gauges

Tools necessary for operation

It is necessary to open a couple of windows to be ready to operate the vacuum system. You must be operating from one of the hutch computer (mec-daq, mec-monitor, mec-console, mec-laser, mec-hutch01, mec-laptop08), or you can ssh to these computers.

mechome

In a terminal, type mechome to open the above window. It is the start point of many processes in the MEC system.

MEC Vacuum

In mechome, in the top left part of the window, press the "Vacuum" button to unfold the menu, then select MEC Vacuum to open the above window. It will be used to operate the pumping system components: pumps, gate-valves, etc

tc_vacuum

In a terminal logged as mecopr, type tc_vacuum to open the above window. Often called "striptool", this type of window can display the time evolution of some environmental parameters. Here it shows 4 curves monitoring the pressure value read by 4 different gauges. You can reshape the window and change the time axis range to monitor pressure values over a long time span (~ 1 hour). The curves correspond to the following gauges:
MEC:TC1:GPI:01:PMON   → target chamber Pirani gauge
MEC:TC1:GCC:01:PMON → target chamber Cold-cathode gauge
MEC:SEW:GPI:03:PMON → scroll pump Pirani gauge (Maglev roughing)
MEC:SEW:GPI:04:PMON → scroll pump Pirani gauge (Varian turbo roughing)

Version tracking