Gas Introduction System EiC Training and Refresher · PDF fileGas Introduction System EiC Training and Refresher Course ... • GIM 15 reservoir is batch filled ... Performing Gas

Liam Worth JET EiC Training & Refresher Course 3rd May 2007

Gas Introduction System

EiC Training and Refresher Course

3rd May 2007


Impurities for:-a) Diagnosticsb) Control of plasma

edgec) RF couplingd) Wall deposition

experiments

3HeCD413C MethaneEthaneEthylene Argon Xenon Krypton Nitrogen SilaneNeon

Fuelling Gases:-Hydrogen DeuteriumHelium 4Tritium

Gas Injection Points Gases


Gas Injection Points : Coordinates




Gas Injection Points : Divertor Modules




Gas store

Matrix A Matrix B

GIMs

Local Bottles

Gas Introduction mimic


Gas Introduction System : The Gas Store


Gas Introduction system : Matrix B


Gas Introduction system : Matrix B


Supply isolation valve

Gas Injection Modules (GIMs)

GIMs 1,4 , 5, 6, 7, 8, 9, 10, 11, 12 gas supplied from Matrix . Max pressure = 2.4 bar

1.5 L reservoir

Valve seat

V2 Valve

Local bottle supply valves

Peizo stack


Special Gas Injection Modules : GIM 2

• Constant supply of 700 mbar D2 taken from GDC source cannot be modified from J2

• Injects gas through GDC line 5 into torus at mid-plane octant 1• Mainly used to initiate brake down (low flow puff of gas)• Can be ‘programmed’ (Plasma Density Feedback etc) like the

other GIMS or used for gas puff


Special Gas Injection Modules : GIMs 5 & 6

• Control is same as other GIMs• Can take gas supplied from matrix• Two bottles (10 - 13) fitted locally on each of 5 & 6 in J1T• Local bottles can be selected from J2• Max pressure from local bottles = 2.4 bar• Gas bottles can be changed, but requires access to J1T• Gas from GIM 6 (D2+H2 Mixture) for LH screen



Gas distribution valve box in basement bunker octant 5 GIM 15, with secondary

containment removed





• GIM 15 is doubly contained and is the only GIM on JET that can be used to fuel the plasma with tritium

• Situated on platform at Octant 6• Injects gas directly to the plasma through a high conductance pipe

at the mid plane on Octant 6• Tritium is supplied to GIM 15 from J25 Uranium beds• Max pressure for tritium = 1200 mbar but usually supplied at 950

mbar• GIM 15 reservoir is batch filled (no direct connection to beds)• ‘Hand shaking’ between J2 and J25 to fill done by ST• Other gasses have been supplied, but this is not the norm and is not

encouraged!• Inventories and usage strictly recorded in T2 but can be relaxed on

request


Special Gas Injection Modules : KY7D


Special Gas Injection Modules : KY7D

• KY7D is the gas introduction module which has been used to puff helium into torus for diagnostic calibration

• GIM 13 puffs gas into inner divertor GIM 14 puffs gas into outerdivertor both at Octant 5

• Is not connected to matrix. Local bottle can be fitted on request (lecture size only)

• GIMs 13 & 14 can only puff (i.e. be open or closed)• 0.2 L reservoir with no pumping• Flow rate to reservoir determined by needle valve which has to be

manually set• Flow rate to torus determined by needle valve which has to be

manually set• Programmed form XPSedit


•Will confirm the gas species or gas mixture is as requested.• Verify contamination levels in the fuelling gas are acceptable. Expect to achieve impurity 1 ppb detection limit with new closed ion source system

Gas Species Verification System : New

Has not been commissioned but should be ready for next campaign


Gas Species Verification System : Hardware

• Installed on Matrix B in basement hardware is ready

• Will be able to check gas supply to GIMs from J2

• Currently done by gas puff and RGA in torus or local pulses


Matrix System Diagram


GIM Volumes

GIM V2 Closed V2 open

1 1.5 l 5.762 l

4 1.5 l 5.541 l

5-12 1.466 l 14.7 l

15 0.811 l 3.61l

GIM 2 volume is 1.5 l and is interlocked so that it cannot be operated with V2 open


Gas introduction system : Peizo Valve operation


Peizo Valve Flow Characteristics

Flow vs. pressure ~ linear

Valve does not open until ~ 50 % of voltage dropped.

This effect taken out in calibration where 750 V dropped = 0V control (of 0 to 10)


Operation of Matrix

• Gasses are discussed in Fridays co-ord and the gas schedule is “agreed” before EiC signature


Operation of Matrix

• Vacuum group will ensure that gasses required for the week are loaded on the system in the gas store

• ST will load gassed to Matrix A from the control room• ST will load gasses to GIMs as they are required• The maximum number of gasses that can be selected is 4 from the

matrix + 2 from the local bottles• Speciality gasses are manually loaded to the matrix by vacuum

group


Operation of Matrix

Gas types and initial GIM pressures selected by Shift Technician in accordance to Gas Form on Codas touch panel.

Loading Level 1 Gas Page selects:-

1. GIM pressures2. V2 valves open or closed3. GIM enabled/disabled

GMX has a number of states:-

1. Ready for Countdown2. Ready for Pulse3. Performing Gas Configuration4. Performing Pressure Configuration


Operation of Matrix : useful signals & info

Recorded in CGRTVC/I-GIMn<CMR:001 GIMn reservoir pressureVC/L-PRS-x<GMX x=A,B,C or D Pressure in 4 lines from matrix A to B(if pressure falls below 2 Bar level 3 alarm to ST)

Recorded in JPFVC/I-GIMn<CMR:002 GIMn reservoir pressureVC/I-GIMn<JPF GIMn requested waveformVC/VPD-GIMn<JPF Voltage applied to peizo stack


Operation of Matrix : Timings

• To restore pressures after a pulse ~2 min.• Deliver increase in GIM pressure ~2 min• Reduce pressure on one GIM ~3 min• Reduce pressure on multiple GIMS ~3 min per GIM• Change gas one GIM ~5 min• Change Gas from Matrix A to B ~15 min• Load local bottle ~ 15 min• Complete reconfiguration ~2 hours

These timings have been variable during the last campaign due to problems with the GMX hardware. These

timings should be valid in the future


Plasma Density Feedback (PDF)

Two PDF Feedback Loops

The two loops have similar functionality. The only exceptions are :-

1. The PID gain in the main loop may vary with time (pre-programmed waveform) whereas the PID gain for the secondary loop is a constant.

2. The secondary controller may be turned off when the density in the main loop exceeds a pre-set level.

Output from PDF can be used to control GIMs through PDV


Plasma Density Validation (PDV)

The purpose of the Plasma Density Validation system is to generate reliable density signals for use in real time control systems.

Signals from :- KG1 (Infrared Interferometer) KS3 (Bremsstrahlung)

Density is initially measured using KG1 if the signal quality is lost then KS3 will be used. Once PDV has changed over to using the Bremsstrahlung signal(s) it will not change back to using the KG1.

Output from PDV can be used to control GIMs


PDV Interfaces To Other SystemsPDV interfaces to for this service

CODAS RealTimeSignalServer

All incoming signals and all outgoing signals are routed through RTSS. RTSS performs the logging for all these signals as well as for some generated internally within PDV for debugging purposes.

CentralInterlockSafetySystem The state of PDV is monitored by CISS. A failure of the PDV software generates CISS "Pulse Inhibit".

PlasmaProtectionSsytem Density signal to PulseTerminationNetwork and PlantEnableWindowSystem(interface to heating systems)

Magnetics Plasma current from RTSS. Same signal as is used in PPS.

XLOC in PlasmaPositionCurrentControl

Indicator for plasma phase (Limiter/X-point). Hardwired analogue signal from PPCC to RTSS, which in turn supplies it to PDV .


GIM Control (1)

Control type Description Puff The piezo valve is opened to 100% during a

puff. This is controlled through setting of the puff time window in the pulse schedule.

Dosing (Feed Forward)

The piezo valve is opened according to a pre-programmed waveform. This is controlled by the feed forward waveform and dosing time window in the pulse schedule.

Feedback (main loop) The feed forward waveform is adjusted by the output from the main feedback controller (PID or Adaptive) and then applied to the piezo valve. This setting is controlled through the feedback time window in the pulse schedule. Note that the feedback time window cannot extend outside the feed forward (dosing) time window.


Control Type Description Feedback (secondary loop)

The feed forward waveform is adjusted by the output from the secondary feedback controller (PID or Adaptive) and then applied to the piezo valve. This setting is controlled through the feedback2 time window in the pulse schedule. Note that the feedback2 time window cannot extend outside the feed forward time window.

Fully open/close valve If the feed forward waveform calls for > 99% or < 1% opening of the piezo valve then the valve will be fully opened and closed, respectively, regardless of the any feedback control that may be programmed.

GIM STOP One or more gas modules may be closed (take out of operation) for the remainder of the pulse on receipt of the GIM STOP signal from PTN.

GIM Control (2)


The Order of application of GIM controls

1. GIM STOP signal from PTN.

2. Waveform from RealTimeCuurrentControl. (not generally used)

3. Produce gas puff (100% opening of valve).

4. Feed forward waveform override for fully open/closed valve.

5. Secondary feedback loop correction to feed forward waveform.

6. Main feedback loop correction to feed forward waveform.

7. Feed forward waveform.


On receipt of a SoftStop signal from PTN, PDF will:

1. Take all active GIMs into main loop feedback control.

2. Inhibit inactive GIMs which have later windows programmed.

3. Freeze GIM feed forward waveforms.

4. Ramp down the requested density in proportion to the plasma current.

5. Close all gas valves when plasma current is below a set threshold.


Level 1 Gas Page : Normal


Level 1 Gas Page : Advanced


The gas introduction system : useful information

MOGDOC 10.01 : Tritium Gas Introduction Module 15 -Operation from J2

Tritium & Vacuum website on Intranet (operating instructions)

Contamination is always suspected from GMX and is not always the case. In case of problems call system RO’s (Liam Worth & T Coyne) and/or Vacuum on call

Can always do local pulses, individual GIM 100 % opening for diagnosis

Documents

Gas Introduction System EiC Training and Refresher · PDF fileGas Introduction System EiC Training and Refresher Course ... • GIM 15 reservoir is batch filled ... Performing Gas